1 /*-------------------------------------------------------------------------
4 * This program acts as a clearing house for requests to the
5 * POSTGRES system. Frontend programs send a startup message
6 * to the Postmaster and the postmaster uses the info in the
7 * message to setup a backend process.
9 * The postmaster also manages system-wide operations such as
10 * startup and shutdown. The postmaster itself doesn't do those
11 * operations, mind you --- it just forks off a subprocess to do them
12 * at the right times. It also takes care of resetting the system
13 * if a backend crashes.
15 * The postmaster process creates the shared memory and semaphore
16 * pools during startup, but as a rule does not touch them itself.
17 * In particular, it is not a member of the PGPROC array of backends
18 * and so it cannot participate in lock-manager operations. Keeping
19 * the postmaster away from shared memory operations makes it simpler
20 * and more reliable. The postmaster is almost always able to recover
21 * from crashes of individual backends by resetting shared memory;
22 * if it did much with shared memory then it would be prone to crashing
23 * along with the backends.
25 * When a request message is received, we now fork() immediately.
26 * The child process performs authentication of the request, and
27 * then becomes a backend if successful. This allows the auth code
28 * to be written in a simple single-threaded style (as opposed to the
29 * crufty "poor man's multitasking" code that used to be needed).
30 * More importantly, it ensures that blockages in non-multithreaded
31 * libraries like SSL or PAM cannot cause denial of service to other
35 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
36 * Portions Copyright (c) 1994, Regents of the University of California
40 * src/backend/postmaster/postmaster.c
45 * The Postmaster sets up shared memory data structures
49 * The Postmaster shares memory with the backends but should avoid
50 * touching shared memory, so as not to become stuck if a crashing
51 * backend screws up locks or shared memory. Likewise, the Postmaster
52 * should never block on messages from frontend clients.
55 * The Postmaster cleans up after backends if they have an emergency
56 * exit and/or core dump.
59 * Use write_stderr() only for reporting "interactive" errors
60 * (essentially, bogus arguments on the command line). Once the
61 * postmaster is launched, use ereport().
63 *-------------------------------------------------------------------------
74 #include <sys/socket.h>
76 #include <sys/param.h>
77 #include <netinet/in.h>
78 #include <arpa/inet.h>
82 #ifdef HAVE_SYS_SELECT_H
83 #include <sys/select.h>
94 #include "access/transam.h"
95 #include "access/xlog.h"
96 #include "bootstrap/bootstrap.h"
97 #include "catalog/pg_control.h"
98 #include "lib/ilist.h"
99 #include "libpq/auth.h"
100 #include "libpq/ip.h"
101 #include "libpq/libpq.h"
102 #include "libpq/pqsignal.h"
103 #include "miscadmin.h"
105 #include "postmaster/autovacuum.h"
106 #include "postmaster/bgworker.h"
107 #include "postmaster/fork_process.h"
108 #include "postmaster/pgarch.h"
109 #include "postmaster/postmaster.h"
110 #include "postmaster/syslogger.h"
111 #include "replication/walsender.h"
112 #include "storage/fd.h"
113 #include "storage/ipc.h"
114 #include "storage/pg_shmem.h"
115 #include "storage/pmsignal.h"
116 #include "storage/proc.h"
117 #include "tcop/tcopprot.h"
118 #include "utils/builtins.h"
119 #include "utils/datetime.h"
120 #include "utils/memutils.h"
121 #include "utils/ps_status.h"
122 #include "utils/timeout.h"
125 #include "storage/spin.h"
130 * Possible types of a backend. Beyond being the possible bkend_type values in
131 * struct bkend, these are OR-able request flag bits for SignalSomeChildren()
132 * and CountChildren().
134 #define BACKEND_TYPE_NORMAL 0x0001 /* normal backend */
135 #define BACKEND_TYPE_AUTOVAC 0x0002 /* autovacuum worker process */
136 #define BACKEND_TYPE_WALSND 0x0004 /* walsender process */
137 #define BACKEND_TYPE_BGWORKER 0x0008 /* bgworker process */
138 #define BACKEND_TYPE_ALL 0x000F /* OR of all the above */
140 #define BACKEND_TYPE_WORKER (BACKEND_TYPE_AUTOVAC | BACKEND_TYPE_BGWORKER)
143 * List of active backends (or child processes anyway; we don't actually
144 * know whether a given child has become a backend or is still in the
145 * authorization phase). This is used mainly to keep track of how many
146 * children we have and send them appropriate signals when necessary.
148 * "Special" children such as the startup, bgwriter and autovacuum launcher
149 * tasks are not in this list. Autovacuum worker and walsender are in it.
150 * Also, "dead_end" children are in it: these are children launched just for
151 * the purpose of sending a friendly rejection message to a would-be client.
152 * We must track them because they are attached to shared memory, but we know
153 * they will never become live backends. dead_end children are not assigned a
156 * Background workers that request shared memory access during registration are
161 pid_t pid; /* process id of backend */
162 long cancel_key; /* cancel key for cancels for this backend */
163 int child_slot; /* PMChildSlot for this backend, if any */
166 * Flavor of backend or auxiliary process. Note that BACKEND_TYPE_WALSND
167 * backends initially announce themselves as BACKEND_TYPE_NORMAL, so if
168 * bkend_type is normal, you should check for a recent transition.
171 bool dead_end; /* is it going to send an error and quit? */
172 dlist_node elem; /* list link in BackendList */
175 static dlist_head BackendList = DLIST_STATIC_INIT(BackendList);
178 static Backend *ShmemBackendArray;
183 * List of background workers.
185 * A worker that requests a database connection during registration will have
186 * rw_backend set, and will be present in BackendList. Note: do not rely on
187 * rw_backend being non-NULL for shmem-connected workers!
189 typedef struct RegisteredBgWorker
191 BackgroundWorker rw_worker; /* its registry entry */
192 Backend *rw_backend; /* its BackendList entry, or NULL */
193 pid_t rw_pid; /* 0 if not running */
195 TimestampTz rw_crashed_at; /* if not 0, time it last crashed */
199 slist_node rw_lnode; /* list link */
200 } RegisteredBgWorker;
202 static slist_head BackgroundWorkerList = SLIST_STATIC_INIT(BackgroundWorkerList);
204 BackgroundWorker *MyBgworkerEntry = NULL;
208 /* The socket number we are listening for connections on */
210 /* The directory names for Unix socket(s) */
211 char *Unix_socket_directories;
212 /* The TCP listen address(es) */
213 char *ListenAddresses;
216 * ReservedBackends is the number of backends reserved for superuser use.
217 * This number is taken out of the pool size given by MaxBackends so
218 * number of backend slots available to non-superusers is
219 * (MaxBackends - ReservedBackends). Note what this really means is
220 * "if there are <= ReservedBackends connections available, only superusers
221 * can make new connections" --- pre-existing superuser connections don't
222 * count against the limit.
224 int ReservedBackends;
226 /* The socket(s) we're listening to. */
228 static pgsocket ListenSocket[MAXLISTEN];
231 * Set by the -o option
233 static char ExtraOptions[MAXPGPATH];
236 * These globals control the behavior of the postmaster in case some
237 * backend dumps core. Normally, it kills all peers of the dead backend
238 * and reinitializes shared memory. By specifying -s or -n, we can have
239 * the postmaster stop (rather than kill) peers and not reinitialize
240 * shared data structures. (Reinit is currently dead code, though.)
242 static bool Reinit = true;
243 static int SendStop = false;
245 /* still more option variables */
246 bool EnableSSL = false;
248 int PreAuthDelay = 0;
249 int AuthenticationTimeout = 60;
251 bool log_hostname; /* for ps display and logging */
252 bool Log_connections = false;
253 bool Db_user_namespace = false;
255 bool enable_bonjour = false;
257 bool restart_after_crash = true;
259 char *output_config_variable = NULL;
261 /* PIDs of special child processes; 0 when not running */
262 static pid_t StartupPID = 0,
272 /* Startup/shutdown state */
274 #define SmartShutdown 1
275 #define FastShutdown 2
277 static int Shutdown = NoShutdown;
279 static bool FatalError = false; /* T if recovering from backend crash */
280 static bool RecoveryError = false; /* T if WAL recovery failed */
283 * We use a simple state machine to control startup, shutdown, and
284 * crash recovery (which is rather like shutdown followed by startup).
286 * After doing all the postmaster initialization work, we enter PM_STARTUP
287 * state and the startup process is launched. The startup process begins by
288 * reading the control file and other preliminary initialization steps.
289 * In a normal startup, or after crash recovery, the startup process exits
290 * with exit code 0 and we switch to PM_RUN state. However, archive recovery
291 * is handled specially since it takes much longer and we would like to support
292 * hot standby during archive recovery.
294 * When the startup process is ready to start archive recovery, it signals the
295 * postmaster, and we switch to PM_RECOVERY state. The background writer and
296 * checkpointer are launched, while the startup process continues applying WAL.
297 * If Hot Standby is enabled, then, after reaching a consistent point in WAL
298 * redo, startup process signals us again, and we switch to PM_HOT_STANDBY
299 * state and begin accepting connections to perform read-only queries. When
300 * archive recovery is finished, the startup process exits with exit code 0
301 * and we switch to PM_RUN state.
303 * Normal child backends can only be launched when we are in PM_RUN or
304 * PM_HOT_STANDBY state. (We also allow launch of normal
305 * child backends in PM_WAIT_BACKUP state, but only for superusers.)
306 * In other states we handle connection requests by launching "dead_end"
307 * child processes, which will simply send the client an error message and
308 * quit. (We track these in the BackendList so that we can know when they
309 * are all gone; this is important because they're still connected to shared
310 * memory, and would interfere with an attempt to destroy the shmem segment,
311 * possibly leading to SHMALL failure when we try to make a new one.)
312 * In PM_WAIT_DEAD_END state we are waiting for all the dead_end children
313 * to drain out of the system, and therefore stop accepting connection
314 * requests at all until the last existing child has quit (which hopefully
315 * will not be very long).
317 * Notice that this state variable does not distinguish *why* we entered
318 * states later than PM_RUN --- Shutdown and FatalError must be consulted
319 * to find that out. FatalError is never true in PM_RECOVERY_* or PM_RUN
320 * states, nor in PM_SHUTDOWN states (because we don't enter those states
321 * when trying to recover from a crash). It can be true in PM_STARTUP state,
322 * because we don't clear it until we've successfully started WAL redo.
323 * Similarly, RecoveryError means that we have crashed during recovery, and
324 * should not try to restart.
328 PM_INIT, /* postmaster starting */
329 PM_STARTUP, /* waiting for startup subprocess */
330 PM_RECOVERY, /* in archive recovery mode */
331 PM_HOT_STANDBY, /* in hot standby mode */
332 PM_RUN, /* normal "database is alive" state */
333 PM_WAIT_BACKUP, /* waiting for online backup mode to end */
334 PM_WAIT_READONLY, /* waiting for read only backends to exit */
335 PM_WAIT_BACKENDS, /* waiting for live backends to exit */
336 PM_SHUTDOWN, /* waiting for checkpointer to do shutdown
338 PM_SHUTDOWN_2, /* waiting for archiver and walsenders to
340 PM_WAIT_DEAD_END, /* waiting for dead_end children to exit */
341 PM_NO_CHILDREN /* all important children have exited */
344 static PMState pmState = PM_INIT;
346 static bool ReachedNormalRunning = false; /* T if we've reached PM_RUN */
348 bool ClientAuthInProgress = false; /* T during new-client
351 bool redirection_done = false; /* stderr redirected for syslogger? */
353 /* received START_AUTOVAC_LAUNCHER signal */
354 static volatile sig_atomic_t start_autovac_launcher = false;
356 /* the launcher needs to be signalled to communicate some condition */
357 static volatile bool avlauncher_needs_signal = false;
359 /* set when there's a worker that needs to be started up */
360 static volatile bool StartWorkerNeeded = true;
361 static volatile bool HaveCrashedWorker = false;
364 * State for assigning random salts and cancel keys.
365 * Also, the global MyCancelKey passes the cancel key assigned to a given
366 * backend from the postmaster to that backend (via fork).
368 static unsigned int random_seed = 0;
369 static struct timeval random_start_time;
375 #ifdef HAVE_INT_OPTRESET
376 extern int optreset; /* might not be declared by system headers */
380 static DNSServiceRef bonjour_sdref = NULL;
384 * postmaster.c - function prototypes
386 static void unlink_external_pid_file(int status, Datum arg);
387 static void getInstallationPaths(const char *argv0);
388 static void checkDataDir(void);
389 static Port *ConnCreate(int serverFd);
390 static void ConnFree(Port *port);
391 static void reset_shared(int port);
392 static void SIGHUP_handler(SIGNAL_ARGS);
393 static void pmdie(SIGNAL_ARGS);
394 static void reaper(SIGNAL_ARGS);
395 static void sigusr1_handler(SIGNAL_ARGS);
396 static void startup_die(SIGNAL_ARGS);
397 static void dummy_handler(SIGNAL_ARGS);
398 static int GetNumRegisteredBackgroundWorkers(int flags);
399 static void StartupPacketTimeoutHandler(void);
400 static void CleanupBackend(int pid, int exitstatus);
401 static bool CleanupBackgroundWorker(int pid, int exitstatus);
402 static void do_start_bgworker(void);
403 static void HandleChildCrash(int pid, int exitstatus, const char *procname);
404 static void LogChildExit(int lev, const char *procname,
405 int pid, int exitstatus);
406 static void PostmasterStateMachine(void);
407 static void BackendInitialize(Port *port);
408 static void BackendRun(Port *port) __attribute__((noreturn));
409 static void ExitPostmaster(int status) __attribute__((noreturn));
410 static int ServerLoop(void);
411 static int BackendStartup(Port *port);
412 static int ProcessStartupPacket(Port *port, bool SSLdone);
413 static void processCancelRequest(Port *port, void *pkt);
414 static int initMasks(fd_set *rmask);
415 static void report_fork_failure_to_client(Port *port, int errnum);
416 static CAC_state canAcceptConnections(void);
417 static long PostmasterRandom(void);
418 static void RandomSalt(char *md5Salt);
419 static void signal_child(pid_t pid, int signal);
420 static bool SignalSomeChildren(int signal, int targets);
421 static bool SignalUnconnectedWorkers(int signal);
423 #define SignalChildren(sig) SignalSomeChildren(sig, BACKEND_TYPE_ALL)
425 static int CountChildren(int target);
426 static int CountUnconnectedWorkers(void);
427 static void StartOneBackgroundWorker(void);
428 static bool CreateOptsFile(int argc, char *argv[], char *fullprogname);
429 static pid_t StartChildProcess(AuxProcType type);
430 static void StartAutovacuumWorker(void);
431 static void InitPostmasterDeathWatchHandle(void);
436 #define WNOHANG 0 /* ignored, so any integer value will do */
438 static pid_t waitpid(pid_t pid, int *exitstatus, int options);
439 static void WINAPI pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired);
441 static HANDLE win32ChildQueue;
448 } win32_deadchild_waitinfo;
451 static pid_t backend_forkexec(Port *port);
452 static pid_t internal_forkexec(int argc, char *argv[], Port *port);
454 /* Type for a socket that can be inherited to a client process */
458 SOCKET origsocket; /* Original socket value, or PGINVALID_SOCKET
460 WSAPROTOCOL_INFO wsainfo;
463 typedef int InheritableSocket;
466 typedef struct LWLock LWLock; /* ugly kluge */
469 * Structure contains all variables passed to exec:ed backends
474 InheritableSocket portsocket;
475 char DataDir[MAXPGPATH];
476 pgsocket ListenSocket[MAXLISTEN];
480 unsigned long UsedShmemSegID;
482 HANDLE UsedShmemSegID;
484 void *UsedShmemSegAddr;
486 VariableCache ShmemVariableCache;
487 Backend *ShmemBackendArray;
489 slock_t *ProcStructLock;
490 PROC_HDR *ProcGlobal;
491 PGPROC *AuxiliaryProcs;
492 PGPROC *PreparedXactProcs;
493 PMSignalData *PMSignalState;
494 InheritableSocket pgStatSock;
496 TimestampTz PgStartTime;
497 TimestampTz PgReloadTime;
498 pg_time_t first_syslogger_file_time;
499 bool redirection_done;
500 bool IsBinaryUpgrade;
504 HANDLE PostmasterHandle;
505 HANDLE initial_signal_pipe;
506 HANDLE syslogPipe[2];
508 int postmaster_alive_fds[2];
511 char my_exec_path[MAXPGPATH];
512 char pkglib_path[MAXPGPATH];
513 char ExtraOptions[MAXPGPATH];
516 static void read_backend_variables(char *id, Port *port);
517 static void restore_backend_variables(BackendParameters *param, Port *port);
520 static bool save_backend_variables(BackendParameters *param, Port *port);
522 static bool save_backend_variables(BackendParameters *param, Port *port,
523 HANDLE childProcess, pid_t childPid);
526 static void ShmemBackendArrayAdd(Backend *bn);
527 static void ShmemBackendArrayRemove(Backend *bn);
529 static BackgroundWorker *find_bgworker_entry(int cookie);
530 #endif /* EXEC_BACKEND */
532 #define StartupDataBase() StartChildProcess(StartupProcess)
533 #define StartBackgroundWriter() StartChildProcess(BgWriterProcess)
534 #define StartCheckpointer() StartChildProcess(CheckpointerProcess)
535 #define StartWalWriter() StartChildProcess(WalWriterProcess)
536 #define StartWalReceiver() StartChildProcess(WalReceiverProcess)
538 /* Macros to check exit status of a child process */
539 #define EXIT_STATUS_0(st) ((st) == 0)
540 #define EXIT_STATUS_1(st) (WIFEXITED(st) && WEXITSTATUS(st) == 1)
544 * File descriptors for pipe used to monitor if postmaster is alive.
545 * First is POSTMASTER_FD_WATCH, second is POSTMASTER_FD_OWN.
547 int postmaster_alive_fds[2] = {-1, -1};
549 /* Process handle of postmaster used for the same purpose on Windows */
550 HANDLE PostmasterHandle;
554 * Postmaster main entry point
557 PostmasterMain(int argc, char *argv[])
561 char *userDoption = NULL;
562 bool listen_addr_saved = false;
565 MyProcPid = PostmasterPid = getpid();
567 MyStartTime = time(NULL);
569 IsPostmasterEnvironment = true;
572 * for security, no dir or file created can be group or other accessible
574 umask(S_IRWXG | S_IRWXO);
577 * Fire up essential subsystems: memory management
582 * By default, palloc() requests in the postmaster will be allocated in
583 * the PostmasterContext, which is space that can be recycled by backends.
584 * Allocated data that needs to be available to backends should be
585 * allocated in TopMemoryContext.
587 PostmasterContext = AllocSetContextCreate(TopMemoryContext,
589 ALLOCSET_DEFAULT_MINSIZE,
590 ALLOCSET_DEFAULT_INITSIZE,
591 ALLOCSET_DEFAULT_MAXSIZE);
592 MemoryContextSwitchTo(PostmasterContext);
594 /* Initialize paths to installation files */
595 getInstallationPaths(argv[0]);
600 InitializeGUCOptions();
605 * Parse command-line options. CAUTION: keep this in sync with
606 * tcop/postgres.c (the option sets should not conflict) and with the
607 * common help() function in main/main.c.
609 while ((opt = getopt(argc, argv, "A:B:bc:C:D:d:EeFf:h:ijk:lN:nOo:Pp:r:S:sTt:W:-:")) != -1)
614 SetConfigOption("debug_assertions", optarg, PGC_POSTMASTER, PGC_S_ARGV);
618 SetConfigOption("shared_buffers", optarg, PGC_POSTMASTER, PGC_S_ARGV);
622 /* Undocumented flag used for binary upgrades */
623 IsBinaryUpgrade = true;
627 output_config_variable = strdup(optarg);
631 userDoption = strdup(optarg);
635 set_debug_options(atoi(optarg), PGC_POSTMASTER, PGC_S_ARGV);
639 SetConfigOption("log_statement", "all", PGC_POSTMASTER, PGC_S_ARGV);
643 SetConfigOption("datestyle", "euro", PGC_POSTMASTER, PGC_S_ARGV);
647 SetConfigOption("fsync", "false", PGC_POSTMASTER, PGC_S_ARGV);
651 if (!set_plan_disabling_options(optarg, PGC_POSTMASTER, PGC_S_ARGV))
653 write_stderr("%s: invalid argument for option -f: \"%s\"\n",
660 SetConfigOption("listen_addresses", optarg, PGC_POSTMASTER, PGC_S_ARGV);
664 SetConfigOption("listen_addresses", "*", PGC_POSTMASTER, PGC_S_ARGV);
668 /* only used by interactive backend */
672 SetConfigOption("unix_socket_directories", optarg, PGC_POSTMASTER, PGC_S_ARGV);
676 SetConfigOption("ssl", "true", PGC_POSTMASTER, PGC_S_ARGV);
680 SetConfigOption("max_connections", optarg, PGC_POSTMASTER, PGC_S_ARGV);
684 /* Don't reinit shared mem after abnormal exit */
689 SetConfigOption("allow_system_table_mods", "true", PGC_POSTMASTER, PGC_S_ARGV);
693 /* Other options to pass to the backend on the command line */
694 snprintf(ExtraOptions + strlen(ExtraOptions),
695 sizeof(ExtraOptions) - strlen(ExtraOptions),
700 SetConfigOption("ignore_system_indexes", "true", PGC_POSTMASTER, PGC_S_ARGV);
704 SetConfigOption("port", optarg, PGC_POSTMASTER, PGC_S_ARGV);
708 /* only used by single-user backend */
712 SetConfigOption("work_mem", optarg, PGC_POSTMASTER, PGC_S_ARGV);
716 SetConfigOption("log_statement_stats", "true", PGC_POSTMASTER, PGC_S_ARGV);
722 * In the event that some backend dumps core, send SIGSTOP,
723 * rather than SIGQUIT, to all its peers. This lets the wily
724 * post_hacker collect core dumps from everyone.
731 const char *tmp = get_stats_option_name(optarg);
735 SetConfigOption(tmp, "true", PGC_POSTMASTER, PGC_S_ARGV);
739 write_stderr("%s: invalid argument for option -t: \"%s\"\n",
747 SetConfigOption("post_auth_delay", optarg, PGC_POSTMASTER, PGC_S_ARGV);
756 ParseLongOption(optarg, &name, &value);
761 (errcode(ERRCODE_SYNTAX_ERROR),
762 errmsg("--%s requires a value",
766 (errcode(ERRCODE_SYNTAX_ERROR),
767 errmsg("-c %s requires a value",
771 SetConfigOption(name, value, PGC_POSTMASTER, PGC_S_ARGV);
779 write_stderr("Try \"%s --help\" for more information.\n",
786 * Postmaster accepts no non-option switch arguments.
790 write_stderr("%s: invalid argument: \"%s\"\n",
791 progname, argv[optind]);
792 write_stderr("Try \"%s --help\" for more information.\n",
798 * Locate the proper configuration files and data directory, and read
799 * postgresql.conf for the first time.
801 if (!SelectConfigFiles(userDoption, progname))
804 if (output_config_variable != NULL)
807 * permission is handled because the user is reading inside the data
810 puts(GetConfigOption(output_config_variable, false, false));
814 /* Verify that DataDir looks reasonable */
817 /* And switch working directory into it */
821 * Check for invalid combinations of GUC settings.
823 if (ReservedBackends >= MaxConnections)
825 write_stderr("%s: superuser_reserved_connections must be less than max_connections\n", progname);
828 if (max_wal_senders >= MaxConnections)
830 write_stderr("%s: max_wal_senders must be less than max_connections\n", progname);
833 if (XLogArchiveMode && wal_level == WAL_LEVEL_MINIMAL)
835 (errmsg("WAL archival (archive_mode=on) requires wal_level \"archive\" or \"hot_standby\"")));
836 if (max_wal_senders > 0 && wal_level == WAL_LEVEL_MINIMAL)
838 (errmsg("WAL streaming (max_wal_senders > 0) requires wal_level \"archive\" or \"hot_standby\"")));
841 * Other one-time internal sanity checks can go here, if they are fast.
842 * (Put any slow processing further down, after postmaster.pid creation.)
844 if (!CheckDateTokenTables())
846 write_stderr("%s: invalid datetoken tables, please fix\n", progname);
851 * Now that we are done processing the postmaster arguments, reset
852 * getopt(3) library so that it will work correctly in subprocesses.
855 #ifdef HAVE_INT_OPTRESET
856 optreset = 1; /* some systems need this too */
859 /* For debugging: display postmaster environment */
861 extern char **environ;
865 (errmsg_internal("%s: PostmasterMain: initial environment dump:",
868 (errmsg_internal("-----------------------------------------")));
869 for (p = environ; *p; ++p)
871 (errmsg_internal("\t%s", *p)));
873 (errmsg_internal("-----------------------------------------")));
877 * Create lockfile for data directory.
879 * We want to do this before we try to grab the input sockets, because the
880 * data directory interlock is more reliable than the socket-file
881 * interlock (thanks to whoever decided to put socket files in /tmp :-().
882 * For the same reason, it's best to grab the TCP socket(s) before the
885 CreateDataDirLockFile(true);
888 * Initialize SSL library, if specified.
896 * process any libraries that should be preloaded at postmaster start
898 process_shared_preload_libraries();
901 * Now that loadable modules have had their chance to register background
902 * workers, calculate MaxBackends.
904 InitializeMaxBackends();
907 * Establish input sockets.
909 for (i = 0; i < MAXLISTEN; i++)
910 ListenSocket[i] = PGINVALID_SOCKET;
919 /* Need a modifiable copy of ListenAddresses */
920 rawstring = pstrdup(ListenAddresses);
922 /* Parse string into list of hostnames */
923 if (!SplitIdentifierString(rawstring, ',', &elemlist))
925 /* syntax error in list */
927 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
928 errmsg("invalid list syntax for \"listen_addresses\"")));
933 char *curhost = (char *) lfirst(l);
935 if (strcmp(curhost, "*") == 0)
936 status = StreamServerPort(AF_UNSPEC, NULL,
937 (unsigned short) PostPortNumber,
939 ListenSocket, MAXLISTEN);
941 status = StreamServerPort(AF_UNSPEC, curhost,
942 (unsigned short) PostPortNumber,
944 ListenSocket, MAXLISTEN);
946 if (status == STATUS_OK)
949 /* record the first successful host addr in lockfile */
950 if (!listen_addr_saved)
952 AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, curhost);
953 listen_addr_saved = true;
958 (errmsg("could not create listen socket for \"%s\"",
962 if (!success && elemlist != NIL)
964 (errmsg("could not create any TCP/IP sockets")));
971 /* Register for Bonjour only if we opened TCP socket(s) */
972 if (enable_bonjour && ListenSocket[0] != PGINVALID_SOCKET)
974 DNSServiceErrorType err;
977 * We pass 0 for interface_index, which will result in registering on
978 * all "applicable" interfaces. It's not entirely clear from the
979 * DNS-SD docs whether this would be appropriate if we have bound to
980 * just a subset of the available network interfaces.
982 err = DNSServiceRegister(&bonjour_sdref,
989 htons(PostPortNumber),
994 if (err != kDNSServiceErr_NoError)
995 elog(LOG, "DNSServiceRegister() failed: error code %ld",
999 * We don't bother to read the mDNS daemon's reply, and we expect that
1000 * it will automatically terminate our registration when the socket is
1001 * closed at postmaster termination. So there's nothing more to be
1002 * done here. However, the bonjour_sdref is kept around so that
1003 * forked children can close their copies of the socket.
1008 #ifdef HAVE_UNIX_SOCKETS
1009 if (Unix_socket_directories)
1016 /* Need a modifiable copy of Unix_socket_directories */
1017 rawstring = pstrdup(Unix_socket_directories);
1019 /* Parse string into list of directories */
1020 if (!SplitDirectoriesString(rawstring, ',', &elemlist))
1022 /* syntax error in list */
1024 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1025 errmsg("invalid list syntax for \"unix_socket_directories\"")));
1028 foreach(l, elemlist)
1030 char *socketdir = (char *) lfirst(l);
1032 status = StreamServerPort(AF_UNIX, NULL,
1033 (unsigned short) PostPortNumber,
1035 ListenSocket, MAXLISTEN);
1037 if (status == STATUS_OK)
1040 /* record the first successful Unix socket in lockfile */
1042 AddToDataDirLockFile(LOCK_FILE_LINE_SOCKET_DIR, socketdir);
1046 (errmsg("could not create Unix-domain socket in directory \"%s\"",
1050 if (!success && elemlist != NIL)
1052 (errmsg("could not create any Unix-domain sockets")));
1054 list_free_deep(elemlist);
1060 * check that we have some socket to listen on
1062 if (ListenSocket[0] == PGINVALID_SOCKET)
1064 (errmsg("no socket created for listening")));
1067 * If no valid TCP ports, write an empty line for listen address,
1068 * indicating the Unix socket must be used. Note that this line is not
1069 * added to the lock file until there is a socket backing it.
1071 if (!listen_addr_saved)
1072 AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, "");
1075 * Set up shared memory and semaphores.
1077 reset_shared(PostPortNumber);
1080 * Estimate number of openable files. This must happen after setting up
1081 * semaphores, because on some platforms semaphores count as open files.
1086 * Set reference point for stack-depth checking.
1091 * Initialize pipe (or process handle on Windows) that allows children to
1092 * wake up from sleep on postmaster death.
1094 InitPostmasterDeathWatchHandle();
1099 * Initialize I/O completion port used to deliver list of dead children.
1101 win32ChildQueue = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 1);
1102 if (win32ChildQueue == NULL)
1104 (errmsg("could not create I/O completion port for child queue")));
1108 * Record postmaster options. We delay this till now to avoid recording
1109 * bogus options (eg, NBuffers too high for available memory).
1111 if (!CreateOptsFile(argc, argv, my_exec_path))
1115 /* Write out nondefault GUC settings for child processes to use */
1116 write_nondefault_variables(PGC_POSTMASTER);
1120 * Write the external PID file if requested
1122 if (external_pid_file)
1124 FILE *fpidfile = fopen(external_pid_file, "w");
1128 fprintf(fpidfile, "%d\n", MyProcPid);
1131 /* Make PID file world readable */
1132 if (chmod(external_pid_file, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) != 0)
1133 write_stderr("%s: could not change permissions of external PID file \"%s\": %s\n",
1134 progname, external_pid_file, strerror(errno));
1137 write_stderr("%s: could not write external PID file \"%s\": %s\n",
1138 progname, external_pid_file, strerror(errno));
1140 on_proc_exit(unlink_external_pid_file, 0);
1144 * Set up signal handlers for the postmaster process.
1146 * CAUTION: when changing this list, check for side-effects on the signal
1147 * handling setup of child processes. See tcop/postgres.c,
1148 * bootstrap/bootstrap.c, postmaster/bgwriter.c, postmaster/walwriter.c,
1149 * postmaster/autovacuum.c, postmaster/pgarch.c, postmaster/pgstat.c,
1150 * postmaster/syslogger.c, postmaster/bgworker.c and
1151 * postmaster/checkpointer.c.
1154 PG_SETMASK(&BlockSig);
1156 pqsignal(SIGHUP, SIGHUP_handler); /* reread config file and have
1157 * children do same */
1158 pqsignal(SIGINT, pmdie); /* send SIGTERM and shut down */
1159 pqsignal(SIGQUIT, pmdie); /* send SIGQUIT and die */
1160 pqsignal(SIGTERM, pmdie); /* wait for children and shut down */
1161 pqsignal(SIGALRM, SIG_IGN); /* ignored */
1162 pqsignal(SIGPIPE, SIG_IGN); /* ignored */
1163 pqsignal(SIGUSR1, sigusr1_handler); /* message from child process */
1164 pqsignal(SIGUSR2, dummy_handler); /* unused, reserve for children */
1165 pqsignal(SIGCHLD, reaper); /* handle child termination */
1166 pqsignal(SIGTTIN, SIG_IGN); /* ignored */
1167 pqsignal(SIGTTOU, SIG_IGN); /* ignored */
1168 /* ignore SIGXFSZ, so that ulimit violations work like disk full */
1170 pqsignal(SIGXFSZ, SIG_IGN); /* ignored */
1174 * If enabled, start up syslogger collection subprocess
1176 SysLoggerPID = SysLogger_Start();
1179 * Reset whereToSendOutput from DestDebug (its starting state) to
1180 * DestNone. This stops ereport from sending log messages to stderr unless
1181 * Log_destination permits. We don't do this until the postmaster is
1182 * fully launched, since startup failures may as well be reported to
1185 whereToSendOutput = DestNone;
1188 * Initialize stats collection subsystem (this does NOT start the
1189 * collector process!)
1194 * Initialize the autovacuum subsystem (again, no process start yet)
1199 * Load configuration files for client authentication.
1204 * It makes no sense to continue if we fail to load the HBA file,
1205 * since there is no way to connect to the database in this case.
1208 (errmsg("could not load pg_hba.conf")));
1213 * We can start up without the IDENT file, although it means that you
1214 * cannot log in using any of the authentication methods that need a
1215 * user name mapping. load_ident() already logged the details of
1222 * Remove old temporary files. At this point there can be no other
1223 * Postgres processes running in this directory, so this should be safe.
1225 RemovePgTempFiles();
1228 * Remember postmaster startup time
1230 PgStartTime = GetCurrentTimestamp();
1231 /* PostmasterRandom wants its own copy */
1232 gettimeofday(&random_start_time, NULL);
1235 * We're ready to rock and roll...
1237 StartupPID = StartupDataBase();
1238 Assert(StartupPID != 0);
1239 pmState = PM_STARTUP;
1241 /* Some workers may be scheduled to start now */
1242 StartOneBackgroundWorker();
1244 status = ServerLoop();
1247 * ServerLoop probably shouldn't ever return, but if it does, close down.
1249 ExitPostmaster(status != STATUS_OK);
1251 abort(); /* not reached */
1256 * on_proc_exit callback to delete external_pid_file
1259 unlink_external_pid_file(int status, Datum arg)
1261 if (external_pid_file)
1262 unlink(external_pid_file);
1267 * Compute and check the directory paths to files that are part of the
1268 * installation (as deduced from the postgres executable's own location)
1271 getInstallationPaths(const char *argv0)
1275 /* Locate the postgres executable itself */
1276 if (find_my_exec(argv0, my_exec_path) < 0)
1277 elog(FATAL, "%s: could not locate my own executable path", argv0);
1280 /* Locate executable backend before we change working directory */
1281 if (find_other_exec(argv0, "postgres", PG_BACKEND_VERSIONSTR,
1282 postgres_exec_path) < 0)
1284 (errmsg("%s: could not locate matching postgres executable",
1289 * Locate the pkglib directory --- this has to be set early in case we try
1290 * to load any modules from it in response to postgresql.conf entries.
1292 get_pkglib_path(my_exec_path, pkglib_path);
1295 * Verify that there's a readable directory there; otherwise the Postgres
1296 * installation is incomplete or corrupt. (A typical cause of this
1297 * failure is that the postgres executable has been moved or hardlinked to
1298 * some directory that's not a sibling of the installation lib/
1301 pdir = AllocateDir(pkglib_path);
1304 (errcode_for_file_access(),
1305 errmsg("could not open directory \"%s\": %m",
1307 errhint("This may indicate an incomplete PostgreSQL installation, or that the file \"%s\" has been moved away from its proper location.",
1312 * XXX is it worth similarly checking the share/ directory? If the lib/
1313 * directory is there, then share/ probably is too.
1319 * Validate the proposed data directory
1324 char path[MAXPGPATH];
1326 struct stat stat_buf;
1330 if (stat(DataDir, &stat_buf) != 0)
1332 if (errno == ENOENT)
1334 (errcode_for_file_access(),
1335 errmsg("data directory \"%s\" does not exist",
1339 (errcode_for_file_access(),
1340 errmsg("could not read permissions of directory \"%s\": %m",
1344 /* eventual chdir would fail anyway, but let's test ... */
1345 if (!S_ISDIR(stat_buf.st_mode))
1347 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1348 errmsg("specified data directory \"%s\" is not a directory",
1352 * Check that the directory belongs to my userid; if not, reject.
1354 * This check is an essential part of the interlock that prevents two
1355 * postmasters from starting in the same directory (see CreateLockFile()).
1356 * Do not remove or weaken it.
1358 * XXX can we safely enable this check on Windows?
1360 #if !defined(WIN32) && !defined(__CYGWIN__)
1361 if (stat_buf.st_uid != geteuid())
1363 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1364 errmsg("data directory \"%s\" has wrong ownership",
1366 errhint("The server must be started by the user that owns the data directory.")));
1370 * Check if the directory has group or world access. If so, reject.
1372 * It would be possible to allow weaker constraints (for example, allow
1373 * group access) but we cannot make a general assumption that that is
1374 * okay; for example there are platforms where nearly all users
1375 * customarily belong to the same group. Perhaps this test should be
1378 * XXX temporarily suppress check when on Windows, because there may not
1379 * be proper support for Unix-y file permissions. Need to think of a
1380 * reasonable check to apply on Windows.
1382 #if !defined(WIN32) && !defined(__CYGWIN__)
1383 if (stat_buf.st_mode & (S_IRWXG | S_IRWXO))
1385 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1386 errmsg("data directory \"%s\" has group or world access",
1388 errdetail("Permissions should be u=rwx (0700).")));
1391 /* Look for PG_VERSION before looking for pg_control */
1392 ValidatePgVersion(DataDir);
1394 snprintf(path, sizeof(path), "%s/global/pg_control", DataDir);
1396 fp = AllocateFile(path, PG_BINARY_R);
1399 write_stderr("%s: could not find the database system\n"
1400 "Expected to find it in the directory \"%s\",\n"
1401 "but could not open file \"%s\": %s\n",
1402 progname, DataDir, path, strerror(errno));
1409 * Determine how long should we let ServerLoop sleep.
1411 * In normal conditions we wait at most one minute, to ensure that the other
1412 * background tasks handled by ServerLoop get done even when no requests are
1413 * arriving. However, if there are background workers waiting to be started,
1414 * we don't actually sleep so that they are quickly serviced.
1417 DetermineSleepTime(struct timeval *timeout)
1419 TimestampTz next_wakeup = 0;
1422 * Normal case: either there are no background workers at all, or we're in
1423 * a shutdown sequence (during which we ignore bgworkers altogether).
1425 if (Shutdown > NoShutdown ||
1426 (!StartWorkerNeeded && !HaveCrashedWorker))
1428 timeout->tv_sec = 60;
1429 timeout->tv_usec = 0;
1433 if (StartWorkerNeeded)
1435 timeout->tv_sec = 0;
1436 timeout->tv_usec = 0;
1440 if (HaveCrashedWorker)
1445 * When there are crashed bgworkers, we sleep just long enough that
1446 * they are restarted when they request to be. Scan the list to
1447 * determine the minimum of all wakeup times according to most recent
1448 * crash time and requested restart interval.
1450 slist_foreach(siter, &BackgroundWorkerList)
1452 RegisteredBgWorker *rw;
1453 TimestampTz this_wakeup;
1455 rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
1457 if (rw->rw_crashed_at == 0)
1460 if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART)
1463 this_wakeup = TimestampTzPlusMilliseconds(rw->rw_crashed_at,
1464 1000L * rw->rw_worker.bgw_restart_time);
1465 if (next_wakeup == 0 || this_wakeup < next_wakeup)
1466 next_wakeup = this_wakeup;
1470 if (next_wakeup != 0)
1474 TimestampDifference(GetCurrentTimestamp(), next_wakeup,
1475 &timeout->tv_sec, µsecs);
1476 timeout->tv_usec = microsecs;
1478 /* Ensure we don't exceed one minute */
1479 if (timeout->tv_sec > 60)
1481 timeout->tv_sec = 60;
1482 timeout->tv_usec = 0;
1487 timeout->tv_sec = 60;
1488 timeout->tv_usec = 0;
1493 * Main idle loop of postmaster
1503 last_touch_time = time(NULL);
1505 nSockets = initMasks(&readmask);
1513 * Wait for a connection request to arrive.
1515 * If we are in PM_WAIT_DEAD_END state, then we don't want to accept
1516 * any new connections, so we don't call select() at all; just sleep
1517 * for a little bit with signals unblocked.
1519 memcpy((char *) &rmask, (char *) &readmask, sizeof(fd_set));
1521 PG_SETMASK(&UnBlockSig);
1523 if (pmState == PM_WAIT_DEAD_END)
1525 pg_usleep(100000L); /* 100 msec seems reasonable */
1530 /* must set timeout each time; some OSes change it! */
1531 struct timeval timeout;
1533 DetermineSleepTime(&timeout);
1535 selres = select(nSockets, &rmask, NULL, NULL, &timeout);
1539 * Block all signals until we wait again. (This makes it safe for our
1540 * signal handlers to do nontrivial work.)
1542 PG_SETMASK(&BlockSig);
1544 /* Now check the select() result */
1547 if (errno != EINTR && errno != EWOULDBLOCK)
1550 (errcode_for_socket_access(),
1551 errmsg("select() failed in postmaster: %m")));
1552 return STATUS_ERROR;
1557 * New connection pending on any of our sockets? If so, fork a child
1558 * process to deal with it.
1564 for (i = 0; i < MAXLISTEN; i++)
1566 if (ListenSocket[i] == PGINVALID_SOCKET)
1568 if (FD_ISSET(ListenSocket[i], &rmask))
1572 port = ConnCreate(ListenSocket[i]);
1575 BackendStartup(port);
1578 * We no longer need the open socket or port structure
1581 StreamClose(port->sock);
1588 /* If we have lost the log collector, try to start a new one */
1589 if (SysLoggerPID == 0 && Logging_collector)
1590 SysLoggerPID = SysLogger_Start();
1593 * If no background writer process is running, and we are not in a
1594 * state that prevents it, start one. It doesn't matter if this
1595 * fails, we'll just try again later. Likewise for the checkpointer.
1597 if (pmState == PM_RUN || pmState == PM_RECOVERY ||
1598 pmState == PM_HOT_STANDBY)
1600 if (CheckpointerPID == 0)
1601 CheckpointerPID = StartCheckpointer();
1602 if (BgWriterPID == 0)
1603 BgWriterPID = StartBackgroundWriter();
1607 * Likewise, if we have lost the walwriter process, try to start a new
1608 * one. But this is needed only in normal operation (else we cannot
1609 * be writing any new WAL).
1611 if (WalWriterPID == 0 && pmState == PM_RUN)
1612 WalWriterPID = StartWalWriter();
1615 * If we have lost the autovacuum launcher, try to start a new one. We
1616 * don't want autovacuum to run in binary upgrade mode because
1617 * autovacuum might update relfrozenxid for empty tables before the
1618 * physical files are put in place.
1620 if (!IsBinaryUpgrade && AutoVacPID == 0 &&
1621 (AutoVacuumingActive() || start_autovac_launcher) &&
1624 AutoVacPID = StartAutoVacLauncher();
1625 if (AutoVacPID != 0)
1626 start_autovac_launcher = false; /* signal processed */
1629 /* If we have lost the archiver, try to start a new one */
1630 if (XLogArchivingActive() && PgArchPID == 0 && pmState == PM_RUN)
1631 PgArchPID = pgarch_start();
1633 /* If we have lost the stats collector, try to start a new one */
1634 if (PgStatPID == 0 && pmState == PM_RUN)
1635 PgStatPID = pgstat_start();
1637 /* If we need to signal the autovacuum launcher, do so now */
1638 if (avlauncher_needs_signal)
1640 avlauncher_needs_signal = false;
1641 if (AutoVacPID != 0)
1642 kill(AutoVacPID, SIGUSR2);
1645 /* Get other worker processes running, if needed */
1646 if (StartWorkerNeeded || HaveCrashedWorker)
1647 StartOneBackgroundWorker();
1650 * Touch Unix socket and lock files every 58 minutes, to ensure that
1651 * they are not removed by overzealous /tmp-cleaning tasks. We assume
1652 * no one runs cleaners with cutoff times of less than an hour ...
1655 if (now - last_touch_time >= 58 * SECS_PER_MINUTE)
1658 TouchSocketLockFiles();
1659 last_touch_time = now;
1665 * Initialise the masks for select() for the ports we are listening on.
1666 * Return the number of sockets to listen on.
1669 initMasks(fd_set *rmask)
1676 for (i = 0; i < MAXLISTEN; i++)
1678 int fd = ListenSocket[i];
1680 if (fd == PGINVALID_SOCKET)
1693 * Read a client's startup packet and do something according to it.
1695 * Returns STATUS_OK or STATUS_ERROR, or might call ereport(FATAL) and
1696 * not return at all.
1698 * (Note that ereport(FATAL) stuff is sent to the client, so only use it
1699 * if that's what you want. Return STATUS_ERROR if you don't want to
1700 * send anything to the client, which would typically be appropriate
1701 * if we detect a communications failure.)
1704 ProcessStartupPacket(Port *port, bool SSLdone)
1708 ProtocolVersion proto;
1709 MemoryContext oldcontext;
1711 if (pq_getbytes((char *) &len, 4) == EOF)
1714 * EOF after SSLdone probably means the client didn't like our
1715 * response to NEGOTIATE_SSL_CODE. That's not an error condition, so
1716 * don't clutter the log with a complaint.
1720 (errcode(ERRCODE_PROTOCOL_VIOLATION),
1721 errmsg("incomplete startup packet")));
1722 return STATUS_ERROR;
1728 if (len < (int32) sizeof(ProtocolVersion) ||
1729 len > MAX_STARTUP_PACKET_LENGTH)
1732 (errcode(ERRCODE_PROTOCOL_VIOLATION),
1733 errmsg("invalid length of startup packet")));
1734 return STATUS_ERROR;
1738 * Allocate at least the size of an old-style startup packet, plus one
1739 * extra byte, and make sure all are zeroes. This ensures we will have
1740 * null termination of all strings, in both fixed- and variable-length
1743 if (len <= (int32) sizeof(StartupPacket))
1744 buf = palloc0(sizeof(StartupPacket) + 1);
1746 buf = palloc0(len + 1);
1748 if (pq_getbytes(buf, len) == EOF)
1751 (errcode(ERRCODE_PROTOCOL_VIOLATION),
1752 errmsg("incomplete startup packet")));
1753 return STATUS_ERROR;
1757 * The first field is either a protocol version number or a special
1760 port->proto = proto = ntohl(*((ProtocolVersion *) buf));
1762 if (proto == CANCEL_REQUEST_CODE)
1764 processCancelRequest(port, buf);
1765 /* Not really an error, but we don't want to proceed further */
1766 return STATUS_ERROR;
1769 if (proto == NEGOTIATE_SSL_CODE && !SSLdone)
1774 /* No SSL when disabled or on Unix sockets */
1775 if (!EnableSSL || IS_AF_UNIX(port->laddr.addr.ss_family))
1778 SSLok = 'S'; /* Support for SSL */
1780 SSLok = 'N'; /* No support for SSL */
1784 if (send(port->sock, &SSLok, 1, 0) != 1)
1787 goto retry1; /* if interrupted, just retry */
1789 (errcode_for_socket_access(),
1790 errmsg("failed to send SSL negotiation response: %m")));
1791 return STATUS_ERROR; /* close the connection */
1795 if (SSLok == 'S' && secure_open_server(port) == -1)
1796 return STATUS_ERROR;
1798 /* regular startup packet, cancel, etc packet should follow... */
1799 /* but not another SSL negotiation request */
1800 return ProcessStartupPacket(port, true);
1803 /* Could add additional special packet types here */
1806 * Set FrontendProtocol now so that ereport() knows what format to send if
1807 * we fail during startup.
1809 FrontendProtocol = proto;
1811 /* Check we can handle the protocol the frontend is using. */
1813 if (PG_PROTOCOL_MAJOR(proto) < PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST) ||
1814 PG_PROTOCOL_MAJOR(proto) > PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST) ||
1815 (PG_PROTOCOL_MAJOR(proto) == PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST) &&
1816 PG_PROTOCOL_MINOR(proto) > PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST)))
1818 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1819 errmsg("unsupported frontend protocol %u.%u: server supports %u.0 to %u.%u",
1820 PG_PROTOCOL_MAJOR(proto), PG_PROTOCOL_MINOR(proto),
1821 PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST),
1822 PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST),
1823 PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST))));
1826 * Now fetch parameters out of startup packet and save them into the Port
1827 * structure. All data structures attached to the Port struct must be
1828 * allocated in TopMemoryContext so that they will remain available in a
1829 * running backend (even after PostmasterContext is destroyed). We need
1830 * not worry about leaking this storage on failure, since we aren't in the
1831 * postmaster process anymore.
1833 oldcontext = MemoryContextSwitchTo(TopMemoryContext);
1835 if (PG_PROTOCOL_MAJOR(proto) >= 3)
1837 int32 offset = sizeof(ProtocolVersion);
1840 * Scan packet body for name/option pairs. We can assume any string
1841 * beginning within the packet body is null-terminated, thanks to
1842 * zeroing extra byte above.
1844 port->guc_options = NIL;
1846 while (offset < len)
1848 char *nameptr = ((char *) buf) + offset;
1852 if (*nameptr == '\0')
1853 break; /* found packet terminator */
1854 valoffset = offset + strlen(nameptr) + 1;
1855 if (valoffset >= len)
1856 break; /* missing value, will complain below */
1857 valptr = ((char *) buf) + valoffset;
1859 if (strcmp(nameptr, "database") == 0)
1860 port->database_name = pstrdup(valptr);
1861 else if (strcmp(nameptr, "user") == 0)
1862 port->user_name = pstrdup(valptr);
1863 else if (strcmp(nameptr, "options") == 0)
1864 port->cmdline_options = pstrdup(valptr);
1865 else if (strcmp(nameptr, "replication") == 0)
1867 if (!parse_bool(valptr, &am_walsender))
1869 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1870 errmsg("invalid value for boolean option \"replication\"")));
1874 /* Assume it's a generic GUC option */
1875 port->guc_options = lappend(port->guc_options,
1877 port->guc_options = lappend(port->guc_options,
1880 offset = valoffset + strlen(valptr) + 1;
1884 * If we didn't find a packet terminator exactly at the end of the
1885 * given packet length, complain.
1887 if (offset != len - 1)
1889 (errcode(ERRCODE_PROTOCOL_VIOLATION),
1890 errmsg("invalid startup packet layout: expected terminator as last byte")));
1895 * Get the parameters from the old-style, fixed-width-fields startup
1896 * packet as C strings. The packet destination was cleared first so a
1897 * short packet has zeros silently added. We have to be prepared to
1898 * truncate the pstrdup result for oversize fields, though.
1900 StartupPacket *packet = (StartupPacket *) buf;
1902 port->database_name = pstrdup(packet->database);
1903 if (strlen(port->database_name) > sizeof(packet->database))
1904 port->database_name[sizeof(packet->database)] = '\0';
1905 port->user_name = pstrdup(packet->user);
1906 if (strlen(port->user_name) > sizeof(packet->user))
1907 port->user_name[sizeof(packet->user)] = '\0';
1908 port->cmdline_options = pstrdup(packet->options);
1909 if (strlen(port->cmdline_options) > sizeof(packet->options))
1910 port->cmdline_options[sizeof(packet->options)] = '\0';
1911 port->guc_options = NIL;
1914 /* Check a user name was given. */
1915 if (port->user_name == NULL || port->user_name[0] == '\0')
1917 (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION),
1918 errmsg("no PostgreSQL user name specified in startup packet")));
1920 /* The database defaults to the user name. */
1921 if (port->database_name == NULL || port->database_name[0] == '\0')
1922 port->database_name = pstrdup(port->user_name);
1924 if (Db_user_namespace)
1927 * If user@, it is a global user, remove '@'. We only want to do this
1928 * if there is an '@' at the end and no earlier in the user string or
1929 * they may fake as a local user of another database attaching to this
1932 if (strchr(port->user_name, '@') ==
1933 port->user_name + strlen(port->user_name) - 1)
1934 *strchr(port->user_name, '@') = '\0';
1937 /* Append '@' and dbname */
1940 db_user = palloc(strlen(port->user_name) +
1941 strlen(port->database_name) + 2);
1942 sprintf(db_user, "%s@%s", port->user_name, port->database_name);
1943 port->user_name = db_user;
1948 * Truncate given database and user names to length of a Postgres name.
1949 * This avoids lookup failures when overlength names are given.
1951 if (strlen(port->database_name) >= NAMEDATALEN)
1952 port->database_name[NAMEDATALEN - 1] = '\0';
1953 if (strlen(port->user_name) >= NAMEDATALEN)
1954 port->user_name[NAMEDATALEN - 1] = '\0';
1956 /* Walsender is not related to a particular database */
1958 port->database_name[0] = '\0';
1961 * Done putting stuff in TopMemoryContext.
1963 MemoryContextSwitchTo(oldcontext);
1966 * If we're going to reject the connection due to database state, say so
1967 * now instead of wasting cycles on an authentication exchange. (This also
1968 * allows a pg_ping utility to be written.)
1970 switch (port->canAcceptConnections)
1974 (errcode(ERRCODE_CANNOT_CONNECT_NOW),
1975 errmsg("the database system is starting up")));
1979 (errcode(ERRCODE_CANNOT_CONNECT_NOW),
1980 errmsg("the database system is shutting down")));
1984 (errcode(ERRCODE_CANNOT_CONNECT_NOW),
1985 errmsg("the database system is in recovery mode")));
1989 (errcode(ERRCODE_TOO_MANY_CONNECTIONS),
1990 errmsg("sorry, too many clients already")));
1992 case CAC_WAITBACKUP:
1993 /* OK for now, will check in InitPostgres */
2004 * The client has sent a cancel request packet, not a normal
2005 * start-a-new-connection packet. Perform the necessary processing.
2006 * Nothing is sent back to the client.
2009 processCancelRequest(Port *port, void *pkt)
2011 CancelRequestPacket *canc = (CancelRequestPacket *) pkt;
2013 long cancelAuthCode;
2016 #ifndef EXEC_BACKEND
2022 backendPID = (int) ntohl(canc->backendPID);
2023 cancelAuthCode = (long) ntohl(canc->cancelAuthCode);
2026 * See if we have a matching backend. In the EXEC_BACKEND case, we can no
2027 * longer access the postmaster's own backend list, and must rely on the
2028 * duplicate array in shared memory.
2030 #ifndef EXEC_BACKEND
2031 dlist_foreach(iter, &BackendList)
2033 bp = dlist_container(Backend, elem, iter.cur);
2035 for (i = MaxLivePostmasterChildren() - 1; i >= 0; i--)
2037 bp = (Backend *) &ShmemBackendArray[i];
2039 if (bp->pid == backendPID)
2041 if (bp->cancel_key == cancelAuthCode)
2043 /* Found a match; signal that backend to cancel current op */
2045 (errmsg_internal("processing cancel request: sending SIGINT to process %d",
2047 signal_child(bp->pid, SIGINT);
2050 /* Right PID, wrong key: no way, Jose */
2052 (errmsg("wrong key in cancel request for process %d",
2058 /* No matching backend */
2060 (errmsg("PID %d in cancel request did not match any process",
2065 * canAcceptConnections --- check to see if database state allows connections.
2068 canAcceptConnections(void)
2070 CAC_state result = CAC_OK;
2073 * Can't start backends when in startup/shutdown/inconsistent recovery
2076 * In state PM_WAIT_BACKUP only superusers can connect (this must be
2077 * allowed so that a superuser can end online backup mode); we return
2078 * CAC_WAITBACKUP code to indicate that this must be checked later. Note
2079 * that neither CAC_OK nor CAC_WAITBACKUP can safely be returned until we
2080 * have checked for too many children.
2082 if (pmState != PM_RUN)
2084 if (pmState == PM_WAIT_BACKUP)
2085 result = CAC_WAITBACKUP; /* allow superusers only */
2086 else if (Shutdown > NoShutdown)
2087 return CAC_SHUTDOWN; /* shutdown is pending */
2088 else if (!FatalError &&
2089 (pmState == PM_STARTUP ||
2090 pmState == PM_RECOVERY))
2091 return CAC_STARTUP; /* normal startup */
2092 else if (!FatalError &&
2093 pmState == PM_HOT_STANDBY)
2094 result = CAC_OK; /* connection OK during hot standby */
2096 return CAC_RECOVERY; /* else must be crash recovery */
2100 * Don't start too many children.
2102 * We allow more connections than we can have backends here because some
2103 * might still be authenticating; they might fail auth, or some existing
2104 * backend might exit before the auth cycle is completed. The exact
2105 * MaxBackends limit is enforced when a new backend tries to join the
2106 * shared-inval backend array.
2108 * The limit here must match the sizes of the per-child-process arrays;
2109 * see comments for MaxLivePostmasterChildren().
2111 if (CountChildren(BACKEND_TYPE_ALL) >= MaxLivePostmasterChildren())
2112 result = CAC_TOOMANY;
2119 * ConnCreate -- create a local connection data structure
2121 * Returns NULL on failure, other than out-of-memory which is fatal.
2124 ConnCreate(int serverFd)
2128 if (!(port = (Port *) calloc(1, sizeof(Port))))
2131 (errcode(ERRCODE_OUT_OF_MEMORY),
2132 errmsg("out of memory")));
2136 if (StreamConnection(serverFd, port) != STATUS_OK)
2138 if (port->sock >= 0)
2139 StreamClose(port->sock);
2145 * Precompute password salt values to use for this connection. It's
2146 * slightly annoying to do this long in advance of knowing whether we'll
2147 * need 'em or not, but we must do the random() calls before we fork, not
2148 * after. Else the postmaster's random sequence won't get advanced, and
2149 * all backends would end up using the same salt...
2151 RandomSalt(port->md5Salt);
2154 * Allocate GSSAPI specific state struct
2156 #ifndef EXEC_BACKEND
2157 #if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
2158 port->gss = (pg_gssinfo *) calloc(1, sizeof(pg_gssinfo));
2162 (errcode(ERRCODE_OUT_OF_MEMORY),
2163 errmsg("out of memory")));
2174 * ConnFree -- free a local connection data structure
2177 ConnFree(Port *conn)
2189 * ClosePostmasterPorts -- close all the postmaster's open sockets
2191 * This is called during child process startup to release file descriptors
2192 * that are not needed by that child process. The postmaster still has
2193 * them open, of course.
2195 * Note: we pass am_syslogger as a boolean because we don't want to set
2196 * the global variable yet when this is called.
2199 ClosePostmasterPorts(bool am_syslogger)
2206 * Close the write end of postmaster death watch pipe. It's important to
2207 * do this as early as possible, so that if postmaster dies, others won't
2208 * think that it's still running because we're holding the pipe open.
2210 if (close(postmaster_alive_fds[POSTMASTER_FD_OWN]))
2212 (errcode_for_file_access(),
2213 errmsg_internal("could not close postmaster death monitoring pipe in child process: %m")));
2214 postmaster_alive_fds[POSTMASTER_FD_OWN] = -1;
2217 /* Close the listen sockets */
2218 for (i = 0; i < MAXLISTEN; i++)
2220 if (ListenSocket[i] != PGINVALID_SOCKET)
2222 StreamClose(ListenSocket[i]);
2223 ListenSocket[i] = PGINVALID_SOCKET;
2227 /* If using syslogger, close the read side of the pipe */
2231 if (syslogPipe[0] >= 0)
2232 close(syslogPipe[0]);
2236 CloseHandle(syslogPipe[0]);
2242 /* If using Bonjour, close the connection to the mDNS daemon */
2244 close(DNSServiceRefSockFD(bonjour_sdref));
2250 * reset_shared -- reset shared memory and semaphores
2253 reset_shared(int port)
2256 * Create or re-create shared memory and semaphores.
2258 * Note: in each "cycle of life" we will normally assign the same IPC keys
2259 * (if using SysV shmem and/or semas), since the port number is used to
2260 * determine IPC keys. This helps ensure that we will clean up dead IPC
2261 * objects if the postmaster crashes and is restarted.
2263 CreateSharedMemoryAndSemaphores(false, port);
2268 * SIGHUP -- reread config files, and tell children to do same
2271 SIGHUP_handler(SIGNAL_ARGS)
2273 int save_errno = errno;
2275 PG_SETMASK(&BlockSig);
2277 if (Shutdown <= SmartShutdown)
2280 (errmsg("received SIGHUP, reloading configuration files")));
2281 ProcessConfigFile(PGC_SIGHUP);
2282 SignalChildren(SIGHUP);
2283 SignalUnconnectedWorkers(SIGHUP);
2284 if (StartupPID != 0)
2285 signal_child(StartupPID, SIGHUP);
2286 if (BgWriterPID != 0)
2287 signal_child(BgWriterPID, SIGHUP);
2288 if (CheckpointerPID != 0)
2289 signal_child(CheckpointerPID, SIGHUP);
2290 if (WalWriterPID != 0)
2291 signal_child(WalWriterPID, SIGHUP);
2292 if (WalReceiverPID != 0)
2293 signal_child(WalReceiverPID, SIGHUP);
2294 if (AutoVacPID != 0)
2295 signal_child(AutoVacPID, SIGHUP);
2297 signal_child(PgArchPID, SIGHUP);
2298 if (SysLoggerPID != 0)
2299 signal_child(SysLoggerPID, SIGHUP);
2301 signal_child(PgStatPID, SIGHUP);
2303 /* Reload authentication config files too */
2306 (errmsg("pg_hba.conf not reloaded")));
2310 (errmsg("pg_ident.conf not reloaded")));
2313 /* Update the starting-point file for future children */
2314 write_nondefault_variables(PGC_SIGHUP);
2318 PG_SETMASK(&UnBlockSig);
2325 * pmdie -- signal handler for processing various postmaster signals.
2330 int save_errno = errno;
2332 PG_SETMASK(&BlockSig);
2335 (errmsg_internal("postmaster received signal %d",
2336 postgres_signal_arg)));
2338 switch (postgres_signal_arg)
2345 * Wait for children to end their work, then shut down.
2347 if (Shutdown >= SmartShutdown)
2349 Shutdown = SmartShutdown;
2351 (errmsg("received smart shutdown request")));
2353 if (pmState == PM_RUN || pmState == PM_RECOVERY ||
2354 pmState == PM_HOT_STANDBY || pmState == PM_STARTUP)
2356 /* autovac workers are told to shut down immediately */
2357 /* and bgworkers too; does this need tweaking? */
2358 SignalSomeChildren(SIGTERM,
2359 BACKEND_TYPE_AUTOVAC | BACKEND_TYPE_BGWORKER);
2360 SignalUnconnectedWorkers(SIGTERM);
2361 /* and the autovac launcher too */
2362 if (AutoVacPID != 0)
2363 signal_child(AutoVacPID, SIGTERM);
2364 /* and the bgwriter too */
2365 if (BgWriterPID != 0)
2366 signal_child(BgWriterPID, SIGTERM);
2367 /* and the walwriter too */
2368 if (WalWriterPID != 0)
2369 signal_child(WalWriterPID, SIGTERM);
2372 * If we're in recovery, we can't kill the startup process
2373 * right away, because at present doing so does not release
2374 * its locks. We might want to change this in a future
2375 * release. For the time being, the PM_WAIT_READONLY state
2376 * indicates that we're waiting for the regular (read only)
2377 * backends to die off; once they do, we'll kill the startup
2378 * and walreceiver processes.
2380 pmState = (pmState == PM_RUN) ?
2381 PM_WAIT_BACKUP : PM_WAIT_READONLY;
2385 * Now wait for online backup mode to end and backends to exit. If
2386 * that is already the case, PostmasterStateMachine will take the
2389 PostmasterStateMachine();
2397 * Abort all children with SIGTERM (rollback active transactions
2398 * and exit) and shut down when they are gone.
2400 if (Shutdown >= FastShutdown)
2402 Shutdown = FastShutdown;
2404 (errmsg("received fast shutdown request")));
2406 if (StartupPID != 0)
2407 signal_child(StartupPID, SIGTERM);
2408 if (BgWriterPID != 0)
2409 signal_child(BgWriterPID, SIGTERM);
2410 if (WalReceiverPID != 0)
2411 signal_child(WalReceiverPID, SIGTERM);
2412 SignalUnconnectedWorkers(SIGTERM);
2413 if (pmState == PM_RECOVERY)
2416 * Only startup, bgwriter, walreceiver, unconnected bgworkers,
2417 * and/or checkpointer should be active in this state; we just
2418 * signaled the first four, and we don't want to kill
2421 pmState = PM_WAIT_BACKENDS;
2423 else if (pmState == PM_RUN ||
2424 pmState == PM_WAIT_BACKUP ||
2425 pmState == PM_WAIT_READONLY ||
2426 pmState == PM_WAIT_BACKENDS ||
2427 pmState == PM_HOT_STANDBY)
2430 (errmsg("aborting any active transactions")));
2431 /* shut down all backends and workers */
2432 SignalSomeChildren(SIGTERM,
2433 BACKEND_TYPE_NORMAL | BACKEND_TYPE_AUTOVAC |
2434 BACKEND_TYPE_BGWORKER);
2435 /* and the autovac launcher too */
2436 if (AutoVacPID != 0)
2437 signal_child(AutoVacPID, SIGTERM);
2438 /* and the walwriter too */
2439 if (WalWriterPID != 0)
2440 signal_child(WalWriterPID, SIGTERM);
2441 pmState = PM_WAIT_BACKENDS;
2445 * Now wait for backends to exit. If there are none,
2446 * PostmasterStateMachine will take the next step.
2448 PostmasterStateMachine();
2454 * Immediate Shutdown:
2456 * abort all children with SIGQUIT and exit without attempt to
2457 * properly shut down data base system.
2460 (errmsg("received immediate shutdown request")));
2461 SignalChildren(SIGQUIT);
2462 if (StartupPID != 0)
2463 signal_child(StartupPID, SIGQUIT);
2464 if (BgWriterPID != 0)
2465 signal_child(BgWriterPID, SIGQUIT);
2466 if (CheckpointerPID != 0)
2467 signal_child(CheckpointerPID, SIGQUIT);
2468 if (WalWriterPID != 0)
2469 signal_child(WalWriterPID, SIGQUIT);
2470 if (WalReceiverPID != 0)
2471 signal_child(WalReceiverPID, SIGQUIT);
2472 if (AutoVacPID != 0)
2473 signal_child(AutoVacPID, SIGQUIT);
2475 signal_child(PgArchPID, SIGQUIT);
2477 signal_child(PgStatPID, SIGQUIT);
2478 SignalUnconnectedWorkers(SIGQUIT);
2483 PG_SETMASK(&UnBlockSig);
2489 * Reaper -- signal handler to cleanup after a child process dies.
2494 int save_errno = errno;
2495 int pid; /* process id of dead child process */
2496 int exitstatus; /* its exit status */
2498 PG_SETMASK(&BlockSig);
2501 (errmsg_internal("reaping dead processes")));
2503 while ((pid = waitpid(-1, &exitstatus, WNOHANG)) > 0)
2506 * Check if this child was a startup process.
2508 if (pid == StartupPID)
2513 * Startup process exited in response to a shutdown request (or it
2514 * completed normally regardless of the shutdown request).
2516 if (Shutdown > NoShutdown &&
2517 (EXIT_STATUS_0(exitstatus) || EXIT_STATUS_1(exitstatus)))
2519 pmState = PM_WAIT_BACKENDS;
2520 /* PostmasterStateMachine logic does the rest */
2525 * Unexpected exit of startup process (including FATAL exit)
2526 * during PM_STARTUP is treated as catastrophic. There are no
2527 * other processes running yet, so we can just exit.
2529 if (pmState == PM_STARTUP && !EXIT_STATUS_0(exitstatus))
2531 LogChildExit(LOG, _("startup process"),
2534 (errmsg("aborting startup due to startup process failure")));
2539 * After PM_STARTUP, any unexpected exit (including FATAL exit) of
2540 * the startup process is catastrophic, so kill other children,
2541 * and set RecoveryError so we don't try to reinitialize after
2542 * they're gone. Exception: if FatalError is already set, that
2543 * implies we previously sent the startup process a SIGQUIT, so
2544 * that's probably the reason it died, and we do want to try to
2545 * restart in that case.
2547 if (!EXIT_STATUS_0(exitstatus))
2550 RecoveryError = true;
2551 HandleChildCrash(pid, exitstatus,
2552 _("startup process"));
2557 * Startup succeeded, commence normal operations
2560 ReachedNormalRunning = true;
2564 * Crank up the background tasks, if we didn't do that already
2565 * when we entered consistent recovery state. It doesn't matter
2566 * if this fails, we'll just try again later.
2568 if (CheckpointerPID == 0)
2569 CheckpointerPID = StartCheckpointer();
2570 if (BgWriterPID == 0)
2571 BgWriterPID = StartBackgroundWriter();
2572 if (WalWriterPID == 0)
2573 WalWriterPID = StartWalWriter();
2576 * Likewise, start other special children as needed. In a restart
2577 * situation, some of them may be alive already.
2579 if (!IsBinaryUpgrade && AutoVacuumingActive() && AutoVacPID == 0)
2580 AutoVacPID = StartAutoVacLauncher();
2581 if (XLogArchivingActive() && PgArchPID == 0)
2582 PgArchPID = pgarch_start();
2584 PgStatPID = pgstat_start();
2586 /* some workers may be scheduled to start now */
2587 StartOneBackgroundWorker();
2589 /* at this point we are really open for business */
2591 (errmsg("database system is ready to accept connections")));
2597 * Was it the bgwriter? Normal exit can be ignored; we'll start a new
2598 * one at the next iteration of the postmaster's main loop, if
2599 * necessary. Any other exit condition is treated as a crash.
2601 if (pid == BgWriterPID)
2604 if (!EXIT_STATUS_0(exitstatus))
2605 HandleChildCrash(pid, exitstatus,
2606 _("background writer process"));
2611 * Was it the checkpointer?
2613 if (pid == CheckpointerPID)
2615 CheckpointerPID = 0;
2616 if (EXIT_STATUS_0(exitstatus) && pmState == PM_SHUTDOWN)
2619 * OK, we saw normal exit of the checkpointer after it's been
2620 * told to shut down. We expect that it wrote a shutdown
2621 * checkpoint. (If for some reason it didn't, recovery will
2622 * occur on next postmaster start.)
2624 * At this point we should have no normal backend children
2625 * left (else we'd not be in PM_SHUTDOWN state) but we might
2626 * have dead_end children to wait for.
2628 * If we have an archiver subprocess, tell it to do a last
2629 * archive cycle and quit. Likewise, if we have walsender
2630 * processes, tell them to send any remaining WAL and quit.
2632 Assert(Shutdown > NoShutdown);
2634 /* Waken archiver for the last time */
2636 signal_child(PgArchPID, SIGUSR2);
2639 * Waken walsenders for the last time. No regular backends
2640 * should be around anymore.
2642 SignalChildren(SIGUSR2);
2644 pmState = PM_SHUTDOWN_2;
2647 * We can also shut down the stats collector now; there's
2648 * nothing left for it to do.
2651 signal_child(PgStatPID, SIGQUIT);
2656 * Any unexpected exit of the checkpointer (including FATAL
2657 * exit) is treated as a crash.
2659 HandleChildCrash(pid, exitstatus,
2660 _("checkpointer process"));
2667 * Was it the wal writer? Normal exit can be ignored; we'll start a
2668 * new one at the next iteration of the postmaster's main loop, if
2669 * necessary. Any other exit condition is treated as a crash.
2671 if (pid == WalWriterPID)
2674 if (!EXIT_STATUS_0(exitstatus))
2675 HandleChildCrash(pid, exitstatus,
2676 _("WAL writer process"));
2681 * Was it the wal receiver? If exit status is zero (normal) or one
2682 * (FATAL exit), we assume everything is all right just like normal
2685 if (pid == WalReceiverPID)
2688 if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
2689 HandleChildCrash(pid, exitstatus,
2690 _("WAL receiver process"));
2695 * Was it the autovacuum launcher? Normal exit can be ignored; we'll
2696 * start a new one at the next iteration of the postmaster's main
2697 * loop, if necessary. Any other exit condition is treated as a
2700 if (pid == AutoVacPID)
2703 if (!EXIT_STATUS_0(exitstatus))
2704 HandleChildCrash(pid, exitstatus,
2705 _("autovacuum launcher process"));
2710 * Was it the archiver? If so, just try to start a new one; no need
2711 * to force reset of the rest of the system. (If fail, we'll try
2712 * again in future cycles of the main loop.). Unless we were waiting
2713 * for it to shut down; don't restart it in that case, and
2714 * PostmasterStateMachine() will advance to the next shutdown step.
2716 if (pid == PgArchPID)
2719 if (!EXIT_STATUS_0(exitstatus))
2720 LogChildExit(LOG, _("archiver process"),
2722 if (XLogArchivingActive() && pmState == PM_RUN)
2723 PgArchPID = pgarch_start();
2728 * Was it the statistics collector? If so, just try to start a new
2729 * one; no need to force reset of the rest of the system. (If fail,
2730 * we'll try again in future cycles of the main loop.)
2732 if (pid == PgStatPID)
2735 if (!EXIT_STATUS_0(exitstatus))
2736 LogChildExit(LOG, _("statistics collector process"),
2738 if (pmState == PM_RUN)
2739 PgStatPID = pgstat_start();
2743 /* Was it the system logger? If so, try to start a new one */
2744 if (pid == SysLoggerPID)
2747 /* for safety's sake, launch new logger *first* */
2748 SysLoggerPID = SysLogger_Start();
2749 if (!EXIT_STATUS_0(exitstatus))
2750 LogChildExit(LOG, _("system logger process"),
2755 /* Was it one of our background workers? */
2756 if (CleanupBackgroundWorker(pid, exitstatus))
2758 /* have it be restarted */
2759 HaveCrashedWorker = true;
2764 * Else do standard backend child cleanup.
2766 CleanupBackend(pid, exitstatus);
2767 } /* loop over pending child-death reports */
2770 * After cleaning out the SIGCHLD queue, see if we have any state changes
2771 * or actions to make.
2773 PostmasterStateMachine();
2775 /* Done with signal handler */
2776 PG_SETMASK(&UnBlockSig);
2782 * Scan the bgworkers list and see if the given PID (which has just stopped
2783 * or crashed) is in it. Handle its shutdown if so, and return true. If not a
2784 * bgworker, return false.
2786 * This is heavily based on CleanupBackend. One important difference is that
2787 * we don't know yet that the dying process is a bgworker, so we must be silent
2788 * until we're sure it is.
2791 CleanupBackgroundWorker(int pid,
2792 int exitstatus) /* child's exit status */
2794 char namebuf[MAXPGPATH];
2797 slist_foreach(iter, &BackgroundWorkerList)
2799 RegisteredBgWorker *rw;
2801 rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
2803 if (rw->rw_pid != pid)
2807 /* see CleanupBackend */
2808 if (exitstatus == ERROR_WAIT_NO_CHILDREN)
2812 snprintf(namebuf, MAXPGPATH, "%s: %s", _("worker process"),
2813 rw->rw_worker.bgw_name);
2815 /* Delay restarting any bgworker that exits with a nonzero status. */
2816 if (!EXIT_STATUS_0(exitstatus))
2817 rw->rw_crashed_at = GetCurrentTimestamp();
2819 rw->rw_crashed_at = 0;
2822 * Additionally, for shared-memory-connected workers, just like a
2823 * backend, any exit status other than 0 or 1 is considered a crash
2824 * and causes a system-wide restart.
2826 if (rw->rw_worker.bgw_flags & BGWORKER_SHMEM_ACCESS)
2828 if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
2830 rw->rw_crashed_at = GetCurrentTimestamp();
2831 HandleChildCrash(pid, exitstatus, namebuf);
2836 if (!ReleasePostmasterChildSlot(rw->rw_child_slot))
2839 * Uh-oh, the child failed to clean itself up. Treat as a crash
2842 rw->rw_crashed_at = GetCurrentTimestamp();
2843 HandleChildCrash(pid, exitstatus, namebuf);
2847 /* Get it out of the BackendList and clear out remaining data */
2850 Assert(rw->rw_worker.bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION);
2851 dlist_delete(&rw->rw_backend->elem);
2853 ShmemBackendArrayRemove(rw->rw_backend);
2855 free(rw->rw_backend);
2856 rw->rw_backend = NULL;
2859 rw->rw_child_slot = 0;
2861 LogChildExit(LOG, namebuf, pid, exitstatus);
2870 * CleanupBackend -- cleanup after terminated backend.
2872 * Remove all local state associated with backend.
2874 * If you change this, see also CleanupBackgroundWorker.
2877 CleanupBackend(int pid,
2878 int exitstatus) /* child's exit status. */
2880 dlist_mutable_iter iter;
2882 LogChildExit(DEBUG2, _("server process"), pid, exitstatus);
2885 * If a backend dies in an ugly way then we must signal all other backends
2886 * to quickdie. If exit status is zero (normal) or one (FATAL exit), we
2887 * assume everything is all right and proceed to remove the backend from
2888 * the active backend list.
2893 * On win32, also treat ERROR_WAIT_NO_CHILDREN (128) as nonfatal case,
2894 * since that sometimes happens under load when the process fails to start
2895 * properly (long before it starts using shared memory). Microsoft reports
2896 * it is related to mutex failure:
2897 * http://archives.postgresql.org/pgsql-hackers/2010-09/msg00790.php
2899 if (exitstatus == ERROR_WAIT_NO_CHILDREN)
2901 LogChildExit(LOG, _("server process"), pid, exitstatus);
2906 if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
2908 HandleChildCrash(pid, exitstatus, _("server process"));
2912 dlist_foreach_modify(iter, &BackendList)
2914 Backend *bp = dlist_container(Backend, elem, iter.cur);
2920 if (!ReleasePostmasterChildSlot(bp->child_slot))
2923 * Uh-oh, the child failed to clean itself up. Treat as a
2926 HandleChildCrash(pid, exitstatus, _("server process"));
2930 ShmemBackendArrayRemove(bp);
2933 dlist_delete(iter.cur);
2941 * HandleChildCrash -- cleanup after failed backend, bgwriter, checkpointer,
2942 * walwriter, autovacuum, or background worker.
2944 * The objectives here are to clean up our local state about the child
2945 * process, and to signal all other remaining children to quickdie.
2948 HandleChildCrash(int pid, int exitstatus, const char *procname)
2950 dlist_mutable_iter iter;
2955 * Make log entry unless there was a previous crash (if so, nonzero exit
2956 * status is to be expected in SIGQUIT response; don't clutter log)
2960 LogChildExit(LOG, procname, pid, exitstatus);
2962 (errmsg("terminating any other active server processes")));
2965 /* Process background workers. */
2966 slist_foreach(siter, &BackgroundWorkerList)
2968 RegisteredBgWorker *rw;
2970 rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
2971 if (rw->rw_pid == 0)
2972 continue; /* not running */
2973 if (rw->rw_pid == pid)
2976 * Found entry for freshly-dead worker, so remove it.
2978 (void) ReleasePostmasterChildSlot(rw->rw_child_slot);
2981 dlist_delete(&rw->rw_backend->elem);
2983 ShmemBackendArrayRemove(rw->rw_backend);
2985 free(rw->rw_backend);
2986 rw->rw_backend = NULL;
2989 rw->rw_child_slot = 0;
2990 /* don't reset crashed_at */
2991 /* Keep looping so we can signal remaining workers */
2996 * This worker is still alive. Unless we did so already, tell it
2997 * to commit hara-kiri.
2999 * SIGQUIT is the special signal that says exit without proc_exit
3000 * and let the user know what's going on. But if SendStop is set
3001 * (-s on command line), then we send SIGSTOP instead, so that we
3002 * can get core dumps from all backends by hand.
3007 (errmsg_internal("sending %s to process %d",
3008 (SendStop ? "SIGSTOP" : "SIGQUIT"),
3009 (int) rw->rw_pid)));
3010 signal_child(rw->rw_pid, (SendStop ? SIGSTOP : SIGQUIT));
3015 /* Process regular backends */
3016 dlist_foreach_modify(iter, &BackendList)
3018 bp = dlist_container(Backend, elem, iter.cur);
3023 * Found entry for freshly-dead backend, so remove it.
3027 (void) ReleasePostmasterChildSlot(bp->child_slot);
3029 ShmemBackendArrayRemove(bp);
3032 dlist_delete(iter.cur);
3034 /* Keep looping so we can signal remaining backends */
3039 * This backend is still alive. Unless we did so already, tell it
3040 * to commit hara-kiri.
3042 * SIGQUIT is the special signal that says exit without proc_exit
3043 * and let the user know what's going on. But if SendStop is set
3044 * (-s on command line), then we send SIGSTOP instead, so that we
3045 * can get core dumps from all backends by hand.
3047 * We could exclude dead_end children here, but at least in the
3048 * SIGSTOP case it seems better to include them.
3050 * Background workers were already processed above; ignore them
3053 if (bp->bkend_type == BACKEND_TYPE_BGWORKER)
3059 (errmsg_internal("sending %s to process %d",
3060 (SendStop ? "SIGSTOP" : "SIGQUIT"),
3062 signal_child(bp->pid, (SendStop ? SIGSTOP : SIGQUIT));
3067 /* Take care of the startup process too */
3068 if (pid == StartupPID)
3070 else if (StartupPID != 0 && !FatalError)
3073 (errmsg_internal("sending %s to process %d",
3074 (SendStop ? "SIGSTOP" : "SIGQUIT"),
3075 (int) StartupPID)));
3076 signal_child(StartupPID, (SendStop ? SIGSTOP : SIGQUIT));
3079 /* Take care of the bgwriter too */
3080 if (pid == BgWriterPID)
3082 else if (BgWriterPID != 0 && !FatalError)
3085 (errmsg_internal("sending %s to process %d",
3086 (SendStop ? "SIGSTOP" : "SIGQUIT"),
3087 (int) BgWriterPID)));
3088 signal_child(BgWriterPID, (SendStop ? SIGSTOP : SIGQUIT));
3091 /* Take care of the checkpointer too */
3092 if (pid == CheckpointerPID)
3093 CheckpointerPID = 0;
3094 else if (CheckpointerPID != 0 && !FatalError)
3097 (errmsg_internal("sending %s to process %d",
3098 (SendStop ? "SIGSTOP" : "SIGQUIT"),
3099 (int) CheckpointerPID)));
3100 signal_child(CheckpointerPID, (SendStop ? SIGSTOP : SIGQUIT));
3103 /* Take care of the walwriter too */
3104 if (pid == WalWriterPID)
3106 else if (WalWriterPID != 0 && !FatalError)
3109 (errmsg_internal("sending %s to process %d",
3110 (SendStop ? "SIGSTOP" : "SIGQUIT"),
3111 (int) WalWriterPID)));
3112 signal_child(WalWriterPID, (SendStop ? SIGSTOP : SIGQUIT));
3115 /* Take care of the walreceiver too */
3116 if (pid == WalReceiverPID)
3118 else if (WalReceiverPID != 0 && !FatalError)
3121 (errmsg_internal("sending %s to process %d",
3122 (SendStop ? "SIGSTOP" : "SIGQUIT"),
3123 (int) WalReceiverPID)));
3124 signal_child(WalReceiverPID, (SendStop ? SIGSTOP : SIGQUIT));
3127 /* Take care of the autovacuum launcher too */
3128 if (pid == AutoVacPID)
3130 else if (AutoVacPID != 0 && !FatalError)
3133 (errmsg_internal("sending %s to process %d",
3134 (SendStop ? "SIGSTOP" : "SIGQUIT"),
3135 (int) AutoVacPID)));
3136 signal_child(AutoVacPID, (SendStop ? SIGSTOP : SIGQUIT));
3140 * Force a power-cycle of the pgarch process too. (This isn't absolutely
3141 * necessary, but it seems like a good idea for robustness, and it
3142 * simplifies the state-machine logic in the case where a shutdown request
3143 * arrives during crash processing.)
3145 if (PgArchPID != 0 && !FatalError)
3148 (errmsg_internal("sending %s to process %d",
3151 signal_child(PgArchPID, SIGQUIT);
3155 * Force a power-cycle of the pgstat process too. (This isn't absolutely
3156 * necessary, but it seems like a good idea for robustness, and it
3157 * simplifies the state-machine logic in the case where a shutdown request
3158 * arrives during crash processing.)
3160 if (PgStatPID != 0 && !FatalError)
3163 (errmsg_internal("sending %s to process %d",
3166 signal_child(PgStatPID, SIGQUIT);
3167 allow_immediate_pgstat_restart();
3170 /* We do NOT restart the syslogger */
3173 /* We now transit into a state of waiting for children to die */
3174 if (pmState == PM_RECOVERY ||
3175 pmState == PM_HOT_STANDBY ||
3176 pmState == PM_RUN ||
3177 pmState == PM_WAIT_BACKUP ||
3178 pmState == PM_WAIT_READONLY ||
3179 pmState == PM_SHUTDOWN)
3180 pmState = PM_WAIT_BACKENDS;
3184 * Log the death of a child process.
3187 LogChildExit(int lev, const char *procname, int pid, int exitstatus)
3190 * size of activity_buffer is arbitrary, but set equal to default
3191 * track_activity_query_size
3193 char activity_buffer[1024];
3194 const char *activity = NULL;
3196 if (!EXIT_STATUS_0(exitstatus))
3197 activity = pgstat_get_crashed_backend_activity(pid,
3199 sizeof(activity_buffer));
3201 if (WIFEXITED(exitstatus))
3205 translator: %s is a noun phrase describing a child process, such as
3207 (errmsg("%s (PID %d) exited with exit code %d",
3208 procname, pid, WEXITSTATUS(exitstatus)),
3209 activity ? errdetail("Failed process was running: %s", activity) : 0));
3210 else if (WIFSIGNALED(exitstatus))
3215 translator: %s is a noun phrase describing a child process, such as
3217 (errmsg("%s (PID %d) was terminated by exception 0x%X",
3218 procname, pid, WTERMSIG(exitstatus)),
3219 errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value."),
3220 activity ? errdetail("Failed process was running: %s", activity) : 0));
3221 #elif defined(HAVE_DECL_SYS_SIGLIST) && HAVE_DECL_SYS_SIGLIST
3225 translator: %s is a noun phrase describing a child process, such as
3227 (errmsg("%s (PID %d) was terminated by signal %d: %s",
3228 procname, pid, WTERMSIG(exitstatus),
3229 WTERMSIG(exitstatus) < NSIG ?
3230 sys_siglist[WTERMSIG(exitstatus)] : "(unknown)"),
3231 activity ? errdetail("Failed process was running: %s", activity) : 0));
3236 translator: %s is a noun phrase describing a child process, such as
3238 (errmsg("%s (PID %d) was terminated by signal %d",
3239 procname, pid, WTERMSIG(exitstatus)),
3240 activity ? errdetail("Failed process was running: %s", activity) : 0));
3246 translator: %s is a noun phrase describing a child process, such as
3248 (errmsg("%s (PID %d) exited with unrecognized status %d",
3249 procname, pid, exitstatus),
3250 activity ? errdetail("Failed process was running: %s", activity) : 0));
3254 * Advance the postmaster's state machine and take actions as appropriate
3256 * This is common code for pmdie(), reaper() and sigusr1_handler(), which
3257 * receive the signals that might mean we need to change state.
3260 PostmasterStateMachine(void)
3262 if (pmState == PM_WAIT_BACKUP)
3265 * PM_WAIT_BACKUP state ends when online backup mode is not active.
3267 if (!BackupInProgress())
3268 pmState = PM_WAIT_BACKENDS;
3271 if (pmState == PM_WAIT_READONLY)
3274 * PM_WAIT_READONLY state ends when we have no regular backends that
3275 * have been started during recovery. We kill the startup and
3276 * walreceiver processes and transition to PM_WAIT_BACKENDS. Ideally,
3277 * we might like to kill these processes first and then wait for
3278 * backends to die off, but that doesn't work at present because
3279 * killing the startup process doesn't release its locks.
3281 if (CountChildren(BACKEND_TYPE_NORMAL) == 0)
3283 if (StartupPID != 0)
3284 signal_child(StartupPID, SIGTERM);
3285 if (WalReceiverPID != 0)
3286 signal_child(WalReceiverPID, SIGTERM);
3287 pmState = PM_WAIT_BACKENDS;
3292 * If we are in a state-machine state that implies waiting for backends to
3293 * exit, see if they're all gone, and change state if so.
3295 if (pmState == PM_WAIT_BACKENDS)
3298 * PM_WAIT_BACKENDS state ends when we have no regular backends
3299 * (including autovac workers), no bgworkers (including unconnected
3300 * ones), and no walwriter, autovac launcher or bgwriter. If we are
3301 * doing crash recovery then we expect the checkpointer to exit as
3302 * well, otherwise not. The archiver, stats, and syslogger processes
3303 * are disregarded since they are not connected to shared memory; we
3304 * also disregard dead_end children here. Walsenders are also
3305 * disregarded, they will be terminated later after writing the
3306 * checkpoint record, like the archiver process.
3308 if (CountChildren(BACKEND_TYPE_NORMAL | BACKEND_TYPE_WORKER) == 0 &&
3309 CountUnconnectedWorkers() == 0 &&
3311 WalReceiverPID == 0 &&
3313 (CheckpointerPID == 0 || !FatalError) &&
3314 WalWriterPID == 0 &&
3320 * Start waiting for dead_end children to die. This state
3321 * change causes ServerLoop to stop creating new ones.
3323 pmState = PM_WAIT_DEAD_END;
3326 * We already SIGQUIT'd the archiver and stats processes, if
3327 * any, when we entered FatalError state.
3333 * If we get here, we are proceeding with normal shutdown. All
3334 * the regular children are gone, and it's time to tell the
3335 * checkpointer to do a shutdown checkpoint.
3337 Assert(Shutdown > NoShutdown);
3338 /* Start the checkpointer if not running */
3339 if (CheckpointerPID == 0)
3340 CheckpointerPID = StartCheckpointer();
3341 /* And tell it to shut down */
3342 if (CheckpointerPID != 0)
3344 signal_child(CheckpointerPID, SIGUSR2);
3345 pmState = PM_SHUTDOWN;
3350 * If we failed to fork a checkpointer, just shut down.
3351 * Any required cleanup will happen at next restart. We
3352 * set FatalError so that an "abnormal shutdown" message
3353 * gets logged when we exit.
3356 pmState = PM_WAIT_DEAD_END;
3358 /* Kill the walsenders, archiver and stats collector too */
3359 SignalChildren(SIGQUIT);
3361 signal_child(PgArchPID, SIGQUIT);
3363 signal_child(PgStatPID, SIGQUIT);
3369 if (pmState == PM_SHUTDOWN_2)
3372 * PM_SHUTDOWN_2 state ends when there's no other children than
3373 * dead_end children left. There shouldn't be any regular backends
3374 * left by now anyway; what we're really waiting for is walsenders and
3377 * Walreceiver should normally be dead by now, but not when a fast
3378 * shutdown is performed during recovery.
3380 if (PgArchPID == 0 && CountChildren(BACKEND_TYPE_ALL) == 0 &&
3381 WalReceiverPID == 0)
3383 pmState = PM_WAIT_DEAD_END;
3387 if (pmState == PM_WAIT_DEAD_END)
3390 * PM_WAIT_DEAD_END state ends when the BackendList is entirely empty
3391 * (ie, no dead_end children remain), and the archiver and stats
3392 * collector are gone too.
3394 * The reason we wait for those two is to protect them against a new
3395 * postmaster starting conflicting subprocesses; this isn't an
3396 * ironclad protection, but it at least helps in the
3397 * shutdown-and-immediately-restart scenario. Note that they have
3398 * already been sent appropriate shutdown signals, either during a
3399 * normal state transition leading up to PM_WAIT_DEAD_END, or during
3400 * FatalError processing.
3402 if (dlist_is_empty(&BackendList) &&
3403 PgArchPID == 0 && PgStatPID == 0)
3405 /* These other guys should be dead already */
3406 Assert(StartupPID == 0);
3407 Assert(WalReceiverPID == 0);
3408 Assert(BgWriterPID == 0);
3409 Assert(CheckpointerPID == 0);
3410 Assert(WalWriterPID == 0);
3411 Assert(AutoVacPID == 0);
3412 /* syslogger is not considered here */
3413 pmState = PM_NO_CHILDREN;
3418 * If we've been told to shut down, we exit as soon as there are no
3419 * remaining children. If there was a crash, cleanup will occur at the
3420 * next startup. (Before PostgreSQL 8.3, we tried to recover from the
3421 * crash before exiting, but that seems unwise if we are quitting because
3422 * we got SIGTERM from init --- there may well not be time for recovery
3423 * before init decides to SIGKILL us.)
3425 * Note that the syslogger continues to run. It will exit when it sees
3426 * EOF on its input pipe, which happens when there are no more upstream
3429 if (Shutdown > NoShutdown && pmState == PM_NO_CHILDREN)
3433 ereport(LOG, (errmsg("abnormal database system shutdown")));
3439 * Terminate exclusive backup mode to avoid recovery after a clean
3440 * fast shutdown. Since an exclusive backup can only be taken
3441 * during normal running (and not, for example, while running
3442 * under Hot Standby) it only makes sense to do this if we reached
3443 * normal running. If we're still in recovery, the backup file is
3444 * one we're recovering *from*, and we must keep it around so that
3445 * recovery restarts from the right place.
3447 if (ReachedNormalRunning)
3450 /* Normal exit from the postmaster is here */
3456 * If recovery failed, or the user does not want an automatic restart
3457 * after backend crashes, wait for all non-syslogger children to exit, and
3458 * then exit postmaster. We don't try to reinitialize when recovery fails,
3459 * because more than likely it will just fail again and we will keep
3462 if (pmState == PM_NO_CHILDREN && (RecoveryError || !restart_after_crash))
3466 * If we need to recover from a crash, wait for all non-syslogger children
3467 * to exit, then reset shmem and StartupDataBase.
3469 if (FatalError && pmState == PM_NO_CHILDREN)
3472 (errmsg("all server processes terminated; reinitializing")));
3475 reset_shared(PostPortNumber);
3477 StartupPID = StartupDataBase();
3478 Assert(StartupPID != 0);
3479 pmState = PM_STARTUP;
3485 * Send a signal to a postmaster child process
3487 * On systems that have setsid(), each child process sets itself up as a
3488 * process group leader. For signals that are generally interpreted in the
3489 * appropriate fashion, we signal the entire process group not just the
3490 * direct child process. This allows us to, for example, SIGQUIT a blocked
3491 * archive_recovery script, or SIGINT a script being run by a backend via
3494 * There is a race condition for recently-forked children: they might not
3495 * have executed setsid() yet. So we signal the child directly as well as
3496 * the group. We assume such a child will handle the signal before trying
3497 * to spawn any grandchild processes. We also assume that signaling the
3498 * child twice will not cause any problems.
3501 signal_child(pid_t pid, int signal)
3503 if (kill(pid, signal) < 0)
3504 elog(DEBUG3, "kill(%ld,%d) failed: %m", (long) pid, signal);
3512 if (kill(-pid, signal) < 0)
3513 elog(DEBUG3, "kill(%ld,%d) failed: %m", (long) (-pid), signal);
3522 * Send a signal to bgworkers that did not request backend connections
3524 * The reason this is interesting is that workers that did request connections
3525 * are considered by SignalChildren; this function complements that one.
3528 SignalUnconnectedWorkers(int signal)
3531 bool signaled = false;
3533 slist_foreach(iter, &BackgroundWorkerList)
3535 RegisteredBgWorker *rw;
3537 rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
3539 if (rw->rw_pid == 0)
3541 /* ignore connected workers */
3542 if (rw->rw_backend != NULL)
3546 (errmsg_internal("sending signal %d to process %d",
3547 signal, (int) rw->rw_pid)));
3548 signal_child(rw->rw_pid, signal);
3555 * Send a signal to the targeted children (but NOT special children;
3556 * dead_end children are never signaled, either).
3559 SignalSomeChildren(int signal, int target)
3562 bool signaled = false;
3564 dlist_foreach(iter, &BackendList)
3566 Backend *bp = dlist_container(Backend, elem, iter.cur);
3572 * Since target == BACKEND_TYPE_ALL is the most common case, we test
3573 * it first and avoid touching shared memory for every child.
3575 if (target != BACKEND_TYPE_ALL)
3578 * Assign bkend_type for any recently announced WAL Sender
3581 if (bp->bkend_type == BACKEND_TYPE_NORMAL &&
3582 IsPostmasterChildWalSender(bp->child_slot))
3583 bp->bkend_type = BACKEND_TYPE_WALSND;
3585 if (!(target & bp->bkend_type))
3590 (errmsg_internal("sending signal %d to process %d",
3591 signal, (int) bp->pid)));
3592 signal_child(bp->pid, signal);
3599 * BackendStartup -- start backend process
3601 * returns: STATUS_ERROR if the fork failed, STATUS_OK otherwise.
3603 * Note: if you change this code, also consider StartAutovacuumWorker.
3606 BackendStartup(Port *port)
3608 Backend *bn; /* for backend cleanup */
3612 * Create backend data structure. Better before the fork() so we can
3613 * handle failure cleanly.
3615 bn = (Backend *) malloc(sizeof(Backend));
3619 (errcode(ERRCODE_OUT_OF_MEMORY),
3620 errmsg("out of memory")));
3621 return STATUS_ERROR;
3625 * Compute the cancel key that will be assigned to this backend. The
3626 * backend will have its own copy in the forked-off process' value of
3627 * MyCancelKey, so that it can transmit the key to the frontend.
3629 MyCancelKey = PostmasterRandom();
3630 bn->cancel_key = MyCancelKey;
3632 /* Pass down canAcceptConnections state */
3633 port->canAcceptConnections = canAcceptConnections();
3634 bn->dead_end = (port->canAcceptConnections != CAC_OK &&
3635 port->canAcceptConnections != CAC_WAITBACKUP);
3638 * Unless it's a dead_end child, assign it a child slot number
3641 bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
3646 pid = backend_forkexec(port);
3647 #else /* !EXEC_BACKEND */
3648 pid = fork_process();
3649 if (pid == 0) /* child */
3654 * Let's clean up ourselves as the postmaster child, and close the
3655 * postmaster's listen sockets. (In EXEC_BACKEND case this is all
3656 * done in SubPostmasterMain.)
3658 IsUnderPostmaster = true; /* we are a postmaster subprocess now */
3660 MyProcPid = getpid(); /* reset MyProcPid */
3662 MyStartTime = time(NULL);
3664 /* We don't want the postmaster's proc_exit() handlers */
3667 /* Close the postmaster's sockets */
3668 ClosePostmasterPorts(false);
3670 /* Perform additional initialization and collect startup packet */
3671 BackendInitialize(port);
3673 /* And run the backend */
3676 #endif /* EXEC_BACKEND */
3680 /* in parent, fork failed */
3681 int save_errno = errno;
3684 (void) ReleasePostmasterChildSlot(bn->child_slot);
3688 (errmsg("could not fork new process for connection: %m")));
3689 report_fork_failure_to_client(port, save_errno);
3690 return STATUS_ERROR;
3693 /* in parent, successful fork */
3695 (errmsg_internal("forked new backend, pid=%d socket=%d",
3696 (int) pid, (int) port->sock)));
3699 * Everything's been successful, it's safe to add this backend to our list
3703 bn->bkend_type = BACKEND_TYPE_NORMAL; /* Can change later to WALSND */
3704 dlist_push_head(&BackendList, &bn->elem);
3708 ShmemBackendArrayAdd(bn);
3715 * Try to report backend fork() failure to client before we close the
3716 * connection. Since we do not care to risk blocking the postmaster on
3717 * this connection, we set the connection to non-blocking and try only once.
3719 * This is grungy special-purpose code; we cannot use backend libpq since
3720 * it's not up and running.
3723 report_fork_failure_to_client(Port *port, int errnum)
3728 /* Format the error message packet (always V2 protocol) */
3729 snprintf(buffer, sizeof(buffer), "E%s%s\n",
3730 _("could not fork new process for connection: "),
3733 /* Set port to non-blocking. Don't do send() if this fails */
3734 if (!pg_set_noblock(port->sock))
3737 /* We'll retry after EINTR, but ignore all other failures */
3740 rc = send(port->sock, buffer, strlen(buffer) + 1, 0);
3741 } while (rc < 0 && errno == EINTR);
3746 * BackendInitialize -- initialize an interactive (postmaster-child)
3747 * backend process, and collect the client's startup packet.
3749 * returns: nothing. Will not return at all if there's any failure.
3751 * Note: this code does not depend on having any access to shared memory.
3752 * In the EXEC_BACKEND case, we are physically attached to shared memory
3753 * but have not yet set up most of our local pointers to shmem structures.
3756 BackendInitialize(Port *port)
3760 char remote_host[NI_MAXHOST];
3761 char remote_port[NI_MAXSERV];
3762 char remote_ps_data[NI_MAXHOST];
3764 /* Save port etc. for ps status */
3768 * PreAuthDelay is a debugging aid for investigating problems in the
3769 * authentication cycle: it can be set in postgresql.conf to allow time to
3770 * attach to the newly-forked backend with a debugger. (See also
3771 * PostAuthDelay, which we allow clients to pass through PGOPTIONS, but it
3772 * is not honored until after authentication.)
3774 if (PreAuthDelay > 0)
3775 pg_usleep(PreAuthDelay * 1000000L);
3777 /* This flag will remain set until InitPostgres finishes authentication */
3778 ClientAuthInProgress = true; /* limit visibility of log messages */
3780 /* save process start time */
3781 port->SessionStartTime = GetCurrentTimestamp();
3782 MyStartTime = timestamptz_to_time_t(port->SessionStartTime);
3784 /* set these to empty in case they are needed before we set them up */
3785 port->remote_host = "";
3786 port->remote_port = "";
3789 * Initialize libpq and enable reporting of ereport errors to the client.
3790 * Must do this now because authentication uses libpq to send messages.
3792 pq_init(); /* initialize libpq to talk to client */
3793 whereToSendOutput = DestRemote; /* now safe to ereport to client */
3796 * If possible, make this process a group leader, so that the postmaster
3797 * can signal any child processes too. (We do this now on the off chance
3798 * that something might spawn a child process during authentication.)
3802 elog(FATAL, "setsid() failed: %m");
3806 * We arrange for a simple exit(1) if we receive SIGTERM or SIGQUIT or
3807 * timeout while trying to collect the startup packet. Otherwise the
3808 * postmaster cannot shutdown the database FAST or IMMED cleanly if a
3809 * buggy client fails to send the packet promptly.
3811 pqsignal(SIGTERM, startup_die);
3812 pqsignal(SIGQUIT, startup_die);
3813 InitializeTimeouts(); /* establishes SIGALRM handler */
3814 PG_SETMASK(&StartupBlockSig);
3817 * Get the remote host name and port for logging and status display.
3819 remote_host[0] = '\0';
3820 remote_port[0] = '\0';
3821 if ((ret = pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen,
3822 remote_host, sizeof(remote_host),
3823 remote_port, sizeof(remote_port),
3824 (log_hostname ? 0 : NI_NUMERICHOST) | NI_NUMERICSERV)) != 0)
3826 (errmsg_internal("pg_getnameinfo_all() failed: %s",
3827 gai_strerror(ret))));
3828 if (remote_port[0] == '\0')
3829 snprintf(remote_ps_data, sizeof(remote_ps_data), "%s", remote_host);
3831 snprintf(remote_ps_data, sizeof(remote_ps_data), "%s(%s)", remote_host, remote_port);
3833 if (Log_connections)
3837 (errmsg("connection received: host=%s port=%s",
3842 (errmsg("connection received: host=%s",
3847 * save remote_host and remote_port in port structure
3849 port->remote_host = strdup(remote_host);
3850 port->remote_port = strdup(remote_port);
3852 port->remote_hostname = port->remote_host;
3855 * Ready to begin client interaction. We will give up and exit(1) after a
3856 * time delay, so that a broken client can't hog a connection
3857 * indefinitely. PreAuthDelay and any DNS interactions above don't count
3858 * against the time limit.
3860 * Note: AuthenticationTimeout is applied here while waiting for the
3861 * startup packet, and then again in InitPostgres for the duration of any
3862 * authentication operations. So a hostile client could tie up the
3863 * process for nearly twice AuthenticationTimeout before we kick him off.
3865 * Note: because PostgresMain will call InitializeTimeouts again, the
3866 * registration of STARTUP_PACKET_TIMEOUT will be lost. This is okay
3867 * since we never use it again after this function.
3869 RegisterTimeout(STARTUP_PACKET_TIMEOUT, StartupPacketTimeoutHandler);
3870 enable_timeout_after(STARTUP_PACKET_TIMEOUT, AuthenticationTimeout * 1000);
3873 * Receive the startup packet (which might turn out to be a cancel request
3876 status = ProcessStartupPacket(port, false);
3879 * Stop here if it was bad or a cancel packet. ProcessStartupPacket
3880 * already did any appropriate error reporting.
3882 if (status != STATUS_OK)
3886 * Now that we have the user and database name, we can set the process
3887 * title for ps. It's good to do this as early as possible in startup.
3889 * For a walsender, the ps display is set in the following form:
3891 * postgres: wal sender process <user> <host> <activity>
3893 * To achieve that, we pass "wal sender process" as username and username
3894 * as dbname to init_ps_display(). XXX: should add a new variant of
3895 * init_ps_display() to avoid abusing the parameters like this.
3898 init_ps_display("wal sender process", port->user_name, remote_ps_data,
3899 update_process_title ? "authentication" : "");
3901 init_ps_display(port->user_name, port->database_name, remote_ps_data,
3902 update_process_title ? "authentication" : "");
3905 * Disable the timeout, and prevent SIGTERM/SIGQUIT again.
3907 disable_timeout(STARTUP_PACKET_TIMEOUT, false);
3908 PG_SETMASK(&BlockSig);
3913 * BackendRun -- set up the backend's argument list and invoke PostgresMain()
3916 * Shouldn't return at all.
3917 * If PostgresMain() fails, return status.
3920 BackendRun(Port *port)
3930 * Don't want backend to be able to see the postmaster random number
3931 * generator state. We have to clobber the static random_seed *and* start
3932 * a new random sequence in the random() library function.
3935 random_start_time.tv_usec = 0;
3936 /* slightly hacky way to get integer microseconds part of timestamptz */
3937 TimestampDifference(0, port->SessionStartTime, &secs, &usecs);
3938 srandom((unsigned int) (MyProcPid ^ usecs));
3941 * Now, build the argv vector that will be given to PostgresMain.
3943 * The maximum possible number of commandline arguments that could come
3944 * from ExtraOptions is (strlen(ExtraOptions) + 1) / 2; see
3947 maxac = 2; /* for fixed args supplied below */
3948 maxac += (strlen(ExtraOptions) + 1) / 2;
3950 av = (char **) MemoryContextAlloc(TopMemoryContext,
3951 maxac * sizeof(char *));
3954 av[ac++] = "postgres";
3957 * Pass any backend switches specified with -o on the postmaster's own
3958 * command line. We assume these are secure. (It's OK to mangle
3959 * ExtraOptions now, since we're safely inside a subprocess.)
3961 pg_split_opts(av, &ac, ExtraOptions);
3968 * Debug: print arguments being passed to backend
3971 (errmsg_internal("%s child[%d]: starting with (",
3972 progname, (int) getpid())));
3973 for (i = 0; i < ac; ++i)
3975 (errmsg_internal("\t%s", av[i])));
3977 (errmsg_internal(")")));
3980 * Make sure we aren't in PostmasterContext anymore. (We can't delete it
3981 * just yet, though, because InitPostgres will need the HBA data.)
3983 MemoryContextSwitchTo(TopMemoryContext);
3985 PostgresMain(ac, av, port->database_name, port->user_name);
3992 * postmaster_forkexec -- fork and exec a postmaster subprocess
3994 * The caller must have set up the argv array already, except for argv[2]
3995 * which will be filled with the name of the temp variable file.
3997 * Returns the child process PID, or -1 on fork failure (a suitable error
3998 * message has been logged on failure).
4000 * All uses of this routine will dispatch to SubPostmasterMain in the
4004 postmaster_forkexec(int argc, char *argv[])
4008 /* This entry point passes dummy values for the Port variables */
4009 memset(&port, 0, sizeof(port));
4010 return internal_forkexec(argc, argv, &port);
4014 * backend_forkexec -- fork/exec off a backend process
4016 * Some operating systems (WIN32) don't have fork() so we have to simulate
4017 * it by storing parameters that need to be passed to the child and
4018 * then create a new child process.
4020 * returns the pid of the fork/exec'd process, or -1 on failure
4023 backend_forkexec(Port *port)
4028 av[ac++] = "postgres";
4029 av[ac++] = "--forkbackend";
4030 av[ac++] = NULL; /* filled in by internal_forkexec */
4033 Assert(ac < lengthof(av));
4035 return internal_forkexec(ac, av, port);
4041 * internal_forkexec non-win32 implementation
4043 * - writes out backend variables to the parameter file
4044 * - fork():s, and then exec():s the child process
4047 internal_forkexec(int argc, char *argv[], Port *port)
4049 static unsigned long tmpBackendFileNum = 0;
4051 char tmpfilename[MAXPGPATH];
4052 BackendParameters param;
4055 if (!save_backend_variables(¶m, port))
4056 return -1; /* log made by save_backend_variables */
4058 /* Calculate name for temp file */
4059 snprintf(tmpfilename, MAXPGPATH, "%s/%s.backend_var.%d.%lu",
4060 PG_TEMP_FILES_DIR, PG_TEMP_FILE_PREFIX,
4061 MyProcPid, ++tmpBackendFileNum);
4064 fp = AllocateFile(tmpfilename, PG_BINARY_W);
4068 * As in OpenTemporaryFileInTablespace, try to make the temp-file
4071 mkdir(PG_TEMP_FILES_DIR, S_IRWXU);
4073 fp = AllocateFile(tmpfilename, PG_BINARY_W);
4077 (errcode_for_file_access(),
4078 errmsg("could not create file \"%s\": %m",
4084 if (fwrite(¶m, sizeof(param), 1, fp) != 1)
4087 (errcode_for_file_access(),
4088 errmsg("could not write to file \"%s\": %m", tmpfilename)));
4097 (errcode_for_file_access(),
4098 errmsg("could not write to file \"%s\": %m", tmpfilename)));
4102 /* Make sure caller set up argv properly */
4104 Assert(argv[argc] == NULL);
4105 Assert(strncmp(argv[1], "--fork", 6) == 0);
4106 Assert(argv[2] == NULL);
4108 /* Insert temp file name after --fork argument */
4109 argv[2] = tmpfilename;
4111 /* Fire off execv in child */
4112 if ((pid = fork_process()) == 0)
4114 if (execv(postgres_exec_path, argv) < 0)
4117 (errmsg("could not execute server process \"%s\": %m",
4118 postgres_exec_path)));
4119 /* We're already in the child process here, can't return */
4124 return pid; /* Parent returns pid, or -1 on fork failure */
4129 * internal_forkexec win32 implementation
4131 * - starts backend using CreateProcess(), in suspended state
4132 * - writes out backend variables to the parameter file
4133 * - during this, duplicates handles and sockets required for
4134 * inheritance into the new process
4135 * - resumes execution of the new process once the backend parameter
4139 internal_forkexec(int argc, char *argv[], Port *port)
4142 PROCESS_INFORMATION pi;
4145 char cmdLine[MAXPGPATH * 2];
4147 BackendParameters *param;
4148 SECURITY_ATTRIBUTES sa;
4149 char paramHandleStr[32];
4150 win32_deadchild_waitinfo *childinfo;
4152 /* Make sure caller set up argv properly */
4154 Assert(argv[argc] == NULL);
4155 Assert(strncmp(argv[1], "--fork", 6) == 0);
4156 Assert(argv[2] == NULL);
4158 /* Set up shared memory for parameter passing */
4159 ZeroMemory(&sa, sizeof(sa));
4160 sa.nLength = sizeof(sa);
4161 sa.bInheritHandle = TRUE;
4162 paramHandle = CreateFileMapping(INVALID_HANDLE_VALUE,
4166 sizeof(BackendParameters),
4168 if (paramHandle == INVALID_HANDLE_VALUE)
4170 elog(LOG, "could not create backend parameter file mapping: error code %lu",
4175 param = MapViewOfFile(paramHandle, FILE_MAP_WRITE, 0, 0, sizeof(BackendParameters));
4178 elog(LOG, "could not map backend parameter memory: error code %lu",
4180 CloseHandle(paramHandle);
4184 /* Insert temp file name after --fork argument */
4186 sprintf(paramHandleStr, "%llu", (LONG_PTR) paramHandle);
4188 sprintf(paramHandleStr, "%lu", (DWORD) paramHandle);
4190 argv[2] = paramHandleStr;
4192 /* Format the cmd line */
4193 cmdLine[sizeof(cmdLine) - 1] = '\0';
4194 cmdLine[sizeof(cmdLine) - 2] = '\0';
4195 snprintf(cmdLine, sizeof(cmdLine) - 1, "\"%s\"", postgres_exec_path);
4197 while (argv[++i] != NULL)
4199 j = strlen(cmdLine);
4200 snprintf(cmdLine + j, sizeof(cmdLine) - 1 - j, " \"%s\"", argv[i]);
4202 if (cmdLine[sizeof(cmdLine) - 2] != '\0')
4204 elog(LOG, "subprocess command line too long");
4208 memset(&pi, 0, sizeof(pi));
4209 memset(&si, 0, sizeof(si));
4213 * Create the subprocess in a suspended state. This will be resumed later,
4214 * once we have written out the parameter file.
4216 if (!CreateProcess(NULL, cmdLine, NULL, NULL, TRUE, CREATE_SUSPENDED,
4217 NULL, NULL, &si, &pi))
4219 elog(LOG, "CreateProcess call failed: %m (error code %lu)",
4224 if (!save_backend_variables(param, port, pi.hProcess, pi.dwProcessId))
4227 * log made by save_backend_variables, but we have to clean up the
4228 * mess with the half-started process
4230 if (!TerminateProcess(pi.hProcess, 255))
4232 (errmsg_internal("could not terminate unstarted process: error code %lu",
4234 CloseHandle(pi.hProcess);
4235 CloseHandle(pi.hThread);
4236 return -1; /* log made by save_backend_variables */
4239 /* Drop the parameter shared memory that is now inherited to the backend */
4240 if (!UnmapViewOfFile(param))
4241 elog(LOG, "could not unmap view of backend parameter file: error code %lu",
4243 if (!CloseHandle(paramHandle))
4244 elog(LOG, "could not close handle to backend parameter file: error code %lu",
4248 * Reserve the memory region used by our main shared memory segment before
4249 * we resume the child process.
4251 if (!pgwin32_ReserveSharedMemoryRegion(pi.hProcess))
4254 * Failed to reserve the memory, so terminate the newly created
4255 * process and give up.
4257 if (!TerminateProcess(pi.hProcess, 255))
4259 (errmsg_internal("could not terminate process that failed to reserve memory: error code %lu",
4261 CloseHandle(pi.hProcess);
4262 CloseHandle(pi.hThread);
4263 return -1; /* logging done made by
4264 * pgwin32_ReserveSharedMemoryRegion() */
4268 * Now that the backend variables are written out, we start the child
4269 * thread so it can start initializing while we set up the rest of the
4272 if (ResumeThread(pi.hThread) == -1)
4274 if (!TerminateProcess(pi.hProcess, 255))
4277 (errmsg_internal("could not terminate unstartable process: error code %lu",
4279 CloseHandle(pi.hProcess);
4280 CloseHandle(pi.hThread);
4283 CloseHandle(pi.hProcess);
4284 CloseHandle(pi.hThread);
4286 (errmsg_internal("could not resume thread of unstarted process: error code %lu",
4292 * Queue a waiter for to signal when this child dies. The wait will be
4293 * handled automatically by an operating system thread pool.
4295 * Note: use malloc instead of palloc, since it needs to be thread-safe.
4296 * Struct will be free():d from the callback function that runs on a
4299 childinfo = malloc(sizeof(win32_deadchild_waitinfo));
4302 (errcode(ERRCODE_OUT_OF_MEMORY),
4303 errmsg("out of memory")));
4305 childinfo->procHandle = pi.hProcess;
4306 childinfo->procId = pi.dwProcessId;
4308 if (!RegisterWaitForSingleObject(&childinfo->waitHandle,
4310 pgwin32_deadchild_callback,
4313 WT_EXECUTEONLYONCE | WT_EXECUTEINWAITTHREAD))
4315 (errmsg_internal("could not register process for wait: error code %lu",
4318 /* Don't close pi.hProcess here - the wait thread needs access to it */
4320 CloseHandle(pi.hThread);
4322 return pi.dwProcessId;
4328 * SubPostmasterMain -- Get the fork/exec'd process into a state equivalent
4329 * to what it would be if we'd simply forked on Unix, and then
4330 * dispatch to the appropriate place.
4332 * The first two command line arguments are expected to be "--forkFOO"
4333 * (where FOO indicates which postmaster child we are to become), and
4334 * the name of a variables file that we can read to load data that would
4335 * have been inherited by fork() on Unix. Remaining arguments go to the
4336 * subprocess FooMain() routine.
4339 SubPostmasterMain(int argc, char *argv[])
4343 /* Do this sooner rather than later... */
4344 IsUnderPostmaster = true; /* we are a postmaster subprocess now */
4346 MyProcPid = getpid(); /* reset MyProcPid */
4348 MyStartTime = time(NULL);
4351 * make sure stderr is in binary mode before anything can possibly be
4352 * written to it, in case it's actually the syslogger pipe, so the pipe
4353 * chunking protocol isn't disturbed. Non-logpipe data gets translated on
4354 * redirection (e.g. via pg_ctl -l) anyway.
4357 _setmode(fileno(stderr), _O_BINARY);
4360 /* Lose the postmaster's on-exit routines (really a no-op) */
4363 /* In EXEC_BACKEND case we will not have inherited these settings */
4364 IsPostmasterEnvironment = true;
4365 whereToSendOutput = DestNone;
4367 /* Setup essential subsystems (to ensure elog() behaves sanely) */
4368 MemoryContextInit();
4369 InitializeGUCOptions();
4371 /* Read in the variables file */
4372 memset(&port, 0, sizeof(Port));
4373 read_backend_variables(argv[2], &port);
4376 * Set reference point for stack-depth checking
4381 * Set up memory area for GSS information. Mirrors the code in ConnCreate
4382 * for the non-exec case.
4384 #if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
4385 port.gss = (pg_gssinfo *) calloc(1, sizeof(pg_gssinfo));
4388 (errcode(ERRCODE_OUT_OF_MEMORY),
4389 errmsg("out of memory")));
4392 /* Check we got appropriate args */
4394 elog(FATAL, "invalid subpostmaster invocation");
4397 * If appropriate, physically re-attach to shared memory segment. We want
4398 * to do this before going any further to ensure that we can attach at the
4399 * same address the postmaster used.
4401 if (strcmp(argv[1], "--forkbackend") == 0 ||
4402 strcmp(argv[1], "--forkavlauncher") == 0 ||
4403 strcmp(argv[1], "--forkavworker") == 0 ||
4404 strcmp(argv[1], "--forkboot") == 0 ||
4405 strncmp(argv[1], "--forkbgworker=", 15) == 0)
4406 PGSharedMemoryReAttach();
4408 /* autovacuum needs this set before calling InitProcess */
4409 if (strcmp(argv[1], "--forkavlauncher") == 0)
4410 AutovacuumLauncherIAm();
4411 if (strcmp(argv[1], "--forkavworker") == 0)
4412 AutovacuumWorkerIAm();
4415 * Start our win32 signal implementation. This has to be done after we
4416 * read the backend variables, because we need to pick up the signal pipe
4417 * from the parent process.
4420 pgwin32_signal_initialize();
4423 /* In EXEC_BACKEND case we will not have inherited these settings */
4425 PG_SETMASK(&BlockSig);
4427 /* Read in remaining GUC variables */
4428 read_nondefault_variables();
4431 * Reload any libraries that were preloaded by the postmaster. Since we
4432 * exec'd this process, those libraries didn't come along with us; but we
4433 * should load them into all child processes to be consistent with the
4434 * non-EXEC_BACKEND behavior.
4436 process_shared_preload_libraries();
4438 /* Run backend or appropriate child */
4439 if (strcmp(argv[1], "--forkbackend") == 0)
4441 Assert(argc == 3); /* shouldn't be any more args */
4443 /* Close the postmaster's sockets */
4444 ClosePostmasterPorts(false);
4447 * Need to reinitialize the SSL library in the backend, since the
4448 * context structures contain function pointers and cannot be passed
4449 * through the parameter file.
4451 * XXX should we do this in all child processes? For the moment it's
4452 * enough to do it in backend children.
4456 secure_initialize();
4460 * Perform additional initialization and collect startup packet.
4462 * We want to do this before InitProcess() for a couple of reasons: 1.
4463 * so that we aren't eating up a PGPROC slot while waiting on the
4464 * client. 2. so that if InitProcess() fails due to being out of
4465 * PGPROC slots, we have already initialized libpq and are able to
4466 * report the error to the client.
4468 BackendInitialize(&port);
4470 /* Restore basic shared memory pointers */
4471 InitShmemAccess(UsedShmemSegAddr);
4473 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
4477 * Attach process to shared data structures. If testing EXEC_BACKEND
4478 * on Linux, you must run this as root before starting the postmaster:
4480 * echo 0 >/proc/sys/kernel/randomize_va_space
4482 * This prevents a randomized stack base address that causes child
4483 * shared memory to be at a different address than the parent, making
4484 * it impossible to attached to shared memory. Return the value to
4485 * '1' when finished.
4487 CreateSharedMemoryAndSemaphores(false, 0);
4489 /* And run the backend */
4490 BackendRun(&port); /* does not return */
4492 if (strcmp(argv[1], "--forkboot") == 0)
4494 /* Close the postmaster's sockets */
4495 ClosePostmasterPorts(false);
4497 /* Restore basic shared memory pointers */
4498 InitShmemAccess(UsedShmemSegAddr);
4500 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
4501 InitAuxiliaryProcess();
4503 /* Attach process to shared data structures */
4504 CreateSharedMemoryAndSemaphores(false, 0);
4506 AuxiliaryProcessMain(argc - 2, argv + 2); /* does not return */
4508 if (strcmp(argv[1], "--forkavlauncher") == 0)
4510 /* Close the postmaster's sockets */
4511 ClosePostmasterPorts(false);
4513 /* Restore basic shared memory pointers */
4514 InitShmemAccess(UsedShmemSegAddr);
4516 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
4519 /* Attach process to shared data structures */
4520 CreateSharedMemoryAndSemaphores(false, 0);
4522 AutoVacLauncherMain(argc - 2, argv + 2); /* does not return */
4524 if (strcmp(argv[1], "--forkavworker") == 0)
4526 /* Close the postmaster's sockets */
4527 ClosePostmasterPorts(false);
4529 /* Restore basic shared memory pointers */
4530 InitShmemAccess(UsedShmemSegAddr);
4532 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
4535 /* Attach process to shared data structures */
4536 CreateSharedMemoryAndSemaphores(false, 0);
4538 AutoVacWorkerMain(argc - 2, argv + 2); /* does not return */
4540 if (strncmp(argv[1], "--forkbgworker=", 15) == 0)
4544 /* Close the postmaster's sockets */
4545 ClosePostmasterPorts(false);
4547 /* Restore basic shared memory pointers */
4548 InitShmemAccess(UsedShmemSegAddr);
4550 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
4553 /* Attach process to shared data structures */
4554 CreateSharedMemoryAndSemaphores(false, 0);
4556 cookie = atoi(argv[1] + 15);
4557 MyBgworkerEntry = find_bgworker_entry(cookie);
4558 do_start_bgworker();
4560 if (strcmp(argv[1], "--forkarch") == 0)
4562 /* Close the postmaster's sockets */
4563 ClosePostmasterPorts(false);
4565 /* Do not want to attach to shared memory */
4567 PgArchiverMain(argc, argv); /* does not return */
4569 if (strcmp(argv[1], "--forkcol") == 0)
4571 /* Close the postmaster's sockets */
4572 ClosePostmasterPorts(false);
4574 /* Do not want to attach to shared memory */
4576 PgstatCollectorMain(argc, argv); /* does not return */
4578 if (strcmp(argv[1], "--forklog") == 0)
4580 /* Close the postmaster's sockets */
4581 ClosePostmasterPorts(true);
4583 /* Do not want to attach to shared memory */
4585 SysLoggerMain(argc, argv); /* does not return */
4588 abort(); /* shouldn't get here */
4590 #endif /* EXEC_BACKEND */
4594 * ExitPostmaster -- cleanup
4596 * Do NOT call exit() directly --- always go through here!
4599 ExitPostmaster(int status)
4601 /* should cleanup shared memory and kill all backends */
4604 * Not sure of the semantics here. When the Postmaster dies, should the
4605 * backends all be killed? probably not.
4607 * MUST -- vadim 05-10-1999
4614 * sigusr1_handler - handle signal conditions from child processes
4617 sigusr1_handler(SIGNAL_ARGS)
4619 int save_errno = errno;
4621 PG_SETMASK(&BlockSig);
4624 * RECOVERY_STARTED and BEGIN_HOT_STANDBY signals are ignored in
4625 * unexpected states. If the startup process quickly starts up, completes
4626 * recovery, exits, we might process the death of the startup process
4627 * first. We don't want to go back to recovery in that case.
4629 if (CheckPostmasterSignal(PMSIGNAL_RECOVERY_STARTED) &&
4630 pmState == PM_STARTUP && Shutdown == NoShutdown)
4632 /* WAL redo has started. We're out of reinitialization. */
4636 * Crank up the background tasks. It doesn't matter if this fails,
4637 * we'll just try again later.
4639 Assert(CheckpointerPID == 0);
4640 CheckpointerPID = StartCheckpointer();
4641 Assert(BgWriterPID == 0);
4642 BgWriterPID = StartBackgroundWriter();
4644 pmState = PM_RECOVERY;
4646 if (CheckPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY) &&
4647 pmState == PM_RECOVERY && Shutdown == NoShutdown)
4650 * Likewise, start other special children as needed.
4652 Assert(PgStatPID == 0);
4653 PgStatPID = pgstat_start();
4656 (errmsg("database system is ready to accept read only connections")));
4658 pmState = PM_HOT_STANDBY;
4660 /* Some workers may be scheduled to start now */
4661 StartOneBackgroundWorker();
4664 if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER) &&
4668 * Send SIGUSR1 to archiver process, to wake it up and begin archiving
4669 * next transaction log file.
4671 signal_child(PgArchPID, SIGUSR1);
4674 if (CheckPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE) &&
4677 /* Tell syslogger to rotate logfile */
4678 signal_child(SysLoggerPID, SIGUSR1);
4681 if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER) &&
4682 Shutdown == NoShutdown)
4685 * Start one iteration of the autovacuum daemon, even if autovacuuming
4686 * is nominally not enabled. This is so we can have an active defense
4687 * against transaction ID wraparound. We set a flag for the main loop
4688 * to do it rather than trying to do it here --- this is because the
4689 * autovac process itself may send the signal, and we want to handle
4690 * that by launching another iteration as soon as the current one
4693 start_autovac_launcher = true;
4696 if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER) &&
4697 Shutdown == NoShutdown)
4699 /* The autovacuum launcher wants us to start a worker process. */
4700 StartAutovacuumWorker();
4703 if (CheckPostmasterSignal(PMSIGNAL_START_WALRECEIVER) &&
4704 WalReceiverPID == 0 &&
4705 (pmState == PM_STARTUP || pmState == PM_RECOVERY ||
4706 pmState == PM_HOT_STANDBY || pmState == PM_WAIT_READONLY) &&
4707 Shutdown == NoShutdown)
4709 /* Startup Process wants us to start the walreceiver process. */
4710 WalReceiverPID = StartWalReceiver();
4713 if (CheckPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE) &&
4714 (pmState == PM_WAIT_BACKUP || pmState == PM_WAIT_BACKENDS))
4716 /* Advance postmaster's state machine */
4717 PostmasterStateMachine();
4720 if (CheckPromoteSignal() && StartupPID != 0 &&
4721 (pmState == PM_STARTUP || pmState == PM_RECOVERY ||
4722 pmState == PM_HOT_STANDBY || pmState == PM_WAIT_READONLY))
4724 /* Tell startup process to finish recovery */
4725 signal_child(StartupPID, SIGUSR2);
4728 PG_SETMASK(&UnBlockSig);
4734 * SIGTERM or SIGQUIT while processing startup packet.
4735 * Clean up and exit(1).
4737 * XXX: possible future improvement: try to send a message indicating
4738 * why we are disconnecting. Problem is to be sure we don't block while
4739 * doing so, nor mess up SSL initialization. In practice, if the client
4740 * has wedged here, it probably couldn't do anything with the message anyway.
4743 startup_die(SIGNAL_ARGS)
4749 * Dummy signal handler
4751 * We use this for signals that we don't actually use in the postmaster,
4752 * but we do use in backends. If we were to SIG_IGN such signals in the
4753 * postmaster, then a newly started backend might drop a signal that arrives
4754 * before it's able to reconfigure its signal processing. (See notes in
4758 dummy_handler(SIGNAL_ARGS)
4763 * Timeout while processing startup packet.
4764 * As for startup_die(), we clean up and exit(1).
4767 StartupPacketTimeoutHandler(void)
4777 RandomSalt(char *md5Salt)
4782 * We use % 255, sacrificing one possible byte value, so as to ensure that
4783 * all bits of the random() value participate in the result. While at it,
4784 * add one to avoid generating any null bytes.
4786 rand = PostmasterRandom();
4787 md5Salt[0] = (rand % 255) + 1;
4788 rand = PostmasterRandom();
4789 md5Salt[1] = (rand % 255) + 1;
4790 rand = PostmasterRandom();
4791 md5Salt[2] = (rand % 255) + 1;
4792 rand = PostmasterRandom();
4793 md5Salt[3] = (rand % 255) + 1;
4800 PostmasterRandom(void)
4803 * Select a random seed at the time of first receiving a request.
4805 if (random_seed == 0)
4809 struct timeval random_stop_time;
4811 gettimeofday(&random_stop_time, NULL);
4814 * We are not sure how much precision is in tv_usec, so we swap
4815 * the high and low 16 bits of 'random_stop_time' and XOR them
4816 * with 'random_start_time'. On the off chance that the result is
4817 * 0, we loop until it isn't.
4819 random_seed = random_start_time.tv_usec ^
4820 ((random_stop_time.tv_usec << 16) |
4821 ((random_stop_time.tv_usec >> 16) & 0xffff));
4823 while (random_seed == 0);
4825 srandom(random_seed);
4832 * Count up number of worker processes that did not request backend connections
4833 * See SignalUnconnectedWorkers for why this is interesting.
4836 CountUnconnectedWorkers(void)
4841 slist_foreach(iter, &BackgroundWorkerList)
4843 RegisteredBgWorker *rw;
4845 rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
4847 if (rw->rw_pid == 0)
4849 /* ignore connected workers */
4850 if (rw->rw_backend != NULL)
4859 * Count up number of child processes of specified types (dead_end chidren
4860 * are always excluded).
4863 CountChildren(int target)
4868 dlist_foreach(iter, &BackendList)
4870 Backend *bp = dlist_container(Backend, elem, iter.cur);
4876 * Since target == BACKEND_TYPE_ALL is the most common case, we test
4877 * it first and avoid touching shared memory for every child.
4879 if (target != BACKEND_TYPE_ALL)
4882 * Assign bkend_type for any recently announced WAL Sender
4885 if (bp->bkend_type == BACKEND_TYPE_NORMAL &&
4886 IsPostmasterChildWalSender(bp->child_slot))
4887 bp->bkend_type = BACKEND_TYPE_WALSND;
4889 if (!(target & bp->bkend_type))
4900 * StartChildProcess -- start an auxiliary process for the postmaster
4902 * xlop determines what kind of child will be started. All child types
4903 * initially go to AuxiliaryProcessMain, which will handle common setup.
4905 * Return value of StartChildProcess is subprocess' PID, or 0 if failed
4906 * to start subprocess.
4909 StartChildProcess(AuxProcType type)
4917 * Set up command-line arguments for subprocess
4919 av[ac++] = "postgres";
4922 av[ac++] = "--forkboot";
4923 av[ac++] = NULL; /* filled in by postmaster_forkexec */
4926 snprintf(typebuf, sizeof(typebuf), "-x%d", type);
4930 Assert(ac < lengthof(av));
4933 pid = postmaster_forkexec(ac, av);
4934 #else /* !EXEC_BACKEND */
4935 pid = fork_process();
4937 if (pid == 0) /* child */
4939 IsUnderPostmaster = true; /* we are a postmaster subprocess now */
4941 /* Close the postmaster's sockets */
4942 ClosePostmasterPorts(false);
4944 /* Lose the postmaster's on-exit routines and port connections */
4947 /* Release postmaster's working memory context */
4948 MemoryContextSwitchTo(TopMemoryContext);
4949 MemoryContextDelete(PostmasterContext);
4950 PostmasterContext = NULL;
4952 AuxiliaryProcessMain(ac, av);
4955 #endif /* EXEC_BACKEND */
4959 /* in parent, fork failed */
4960 int save_errno = errno;
4965 case StartupProcess:
4967 (errmsg("could not fork startup process: %m")));
4969 case BgWriterProcess:
4971 (errmsg("could not fork background writer process: %m")));
4973 case CheckpointerProcess:
4975 (errmsg("could not fork checkpointer process: %m")));
4977 case WalWriterProcess:
4979 (errmsg("could not fork WAL writer process: %m")));
4981 case WalReceiverProcess:
4983 (errmsg("could not fork WAL receiver process: %m")));
4987 (errmsg("could not fork process: %m")));
4992 * fork failure is fatal during startup, but there's no need to choke
4993 * immediately if starting other child types fails.
4995 if (type == StartupProcess)
5001 * in parent, successful fork
5007 * StartAutovacuumWorker
5008 * Start an autovac worker process.
5010 * This function is here because it enters the resulting PID into the
5011 * postmaster's private backends list.
5013 * NB -- this code very roughly matches BackendStartup.
5016 StartAutovacuumWorker(void)
5021 * If not in condition to run a process, don't try, but handle it like a
5022 * fork failure. This does not normally happen, since the signal is only
5023 * supposed to be sent by autovacuum launcher when it's OK to do it, but
5024 * we have to check to avoid race-condition problems during DB state
5027 if (canAcceptConnections() == CAC_OK)
5029 bn = (Backend *) malloc(sizeof(Backend));
5033 * Compute the cancel key that will be assigned to this session.
5034 * We probably don't need cancel keys for autovac workers, but
5035 * we'd better have something random in the field to prevent
5036 * unfriendly people from sending cancels to them.
5038 MyCancelKey = PostmasterRandom();
5039 bn->cancel_key = MyCancelKey;
5041 /* Autovac workers are not dead_end and need a child slot */
5042 bn->dead_end = false;
5043 bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
5045 bn->pid = StartAutoVacWorker();
5048 bn->bkend_type = BACKEND_TYPE_AUTOVAC;
5049 dlist_push_head(&BackendList, &bn->elem);
5051 ShmemBackendArrayAdd(bn);
5058 * fork failed, fall through to report -- actual error message was
5059 * logged by StartAutoVacWorker
5061 (void) ReleasePostmasterChildSlot(bn->child_slot);
5066 (errcode(ERRCODE_OUT_OF_MEMORY),
5067 errmsg("out of memory")));
5071 * Report the failure to the launcher, if it's running. (If it's not, we
5072 * might not even be connected to shared memory, so don't try to call
5073 * AutoVacWorkerFailed.) Note that we also need to signal it so that it
5074 * responds to the condition, but we don't do that here, instead waiting
5075 * for ServerLoop to do it. This way we avoid a ping-pong signalling in
5076 * quick succession between the autovac launcher and postmaster in case
5079 if (AutoVacPID != 0)
5081 AutoVacWorkerFailed();
5082 avlauncher_needs_signal = true;
5087 * Create the opts file
5090 CreateOptsFile(int argc, char *argv[], char *fullprogname)
5095 #define OPTS_FILE "postmaster.opts"
5097 if ((fp = fopen(OPTS_FILE, "w")) == NULL)
5099 elog(LOG, "could not create file \"%s\": %m", OPTS_FILE);
5103 fprintf(fp, "%s", fullprogname);
5104 for (i = 1; i < argc; i++)
5105 fprintf(fp, " \"%s\"", argv[i]);
5110 elog(LOG, "could not write file \"%s\": %m", OPTS_FILE);
5119 * MaxLivePostmasterChildren
5121 * This reports the number of entries needed in per-child-process arrays
5122 * (the PMChildFlags array, and if EXEC_BACKEND the ShmemBackendArray).
5123 * These arrays include regular backends, autovac workers, walsenders
5124 * and background workers, but not special children nor dead_end children.
5125 * This allows the arrays to have a fixed maximum size, to wit the same
5126 * too-many-children limit enforced by canAcceptConnections(). The exact value
5127 * isn't too critical as long as it's more than MaxBackends.
5130 MaxLivePostmasterChildren(void)
5132 return 2 * (MaxConnections + autovacuum_max_workers + 1 +
5133 GetNumRegisteredBackgroundWorkers(0));
5137 * Register a new background worker.
5139 * This can only be called in the _PG_init function of a module library
5140 * that's loaded by shared_preload_libraries; otherwise it has no effect.
5143 RegisterBackgroundWorker(BackgroundWorker *worker)
5145 RegisteredBgWorker *rw;
5146 int namelen = strlen(worker->bgw_name);
5147 static int maxworkers;
5148 static int numworkers = 0;
5153 * Use 1 here, not 0, to avoid confusing a possible bogus cookie read by
5154 * atoi() in SubPostmasterMain.
5156 static int BackgroundWorkerCookie = 1;
5159 /* initialize upper limit on first call */
5160 if (numworkers == 0)
5161 maxworkers = MAX_BACKENDS -
5162 (MaxConnections + autovacuum_max_workers + 1);
5164 if (!IsUnderPostmaster)
5166 (errmsg("registering background worker: %s", worker->bgw_name)));
5168 if (!process_shared_preload_libraries_in_progress)
5170 if (!IsUnderPostmaster)
5172 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
5173 errmsg("background worker \"%s\": must be registered in shared_preload_libraries",
5174 worker->bgw_name)));
5178 /* sanity check for flags */
5179 if (worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)
5181 if (!(worker->bgw_flags & BGWORKER_SHMEM_ACCESS))
5183 if (!IsUnderPostmaster)
5185 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
5186 errmsg("background worker \"%s\": must attach to shared memory in order to request a database connection",
5187 worker->bgw_name)));
5191 if (worker->bgw_start_time == BgWorkerStart_PostmasterStart)
5193 if (!IsUnderPostmaster)
5195 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
5196 errmsg("background worker \"%s\": cannot request database access if starting at postmaster start",
5197 worker->bgw_name)));
5201 /* XXX other checks? */
5204 if ((worker->bgw_restart_time < 0 &&
5205 worker->bgw_restart_time != BGW_NEVER_RESTART) ||
5206 (worker->bgw_restart_time > USECS_PER_DAY / 1000))
5208 if (!IsUnderPostmaster)
5210 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
5211 errmsg("background worker \"%s\": invalid restart interval",
5212 worker->bgw_name)));
5217 * Enforce maximum number of workers. Note this is overly restrictive:
5218 * we could allow more non-shmem-connected workers, because these don't
5219 * count towards the MAX_BACKENDS limit elsewhere. This doesn't really
5220 * matter for practical purposes; several million processes would need to
5221 * run on a single server.
5223 if (++numworkers > maxworkers)
5226 (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
5227 errmsg("too many background workers"),
5228 errdetail("Up to %d background workers can be registered with the current settings.",
5234 * Copy the registration data into the registered workers list.
5236 rw = malloc(sizeof(RegisteredBgWorker) + namelen + 1);
5240 (errcode(ERRCODE_OUT_OF_MEMORY),
5241 errmsg("out of memory")));
5245 rw->rw_worker = *worker;
5246 rw->rw_worker.bgw_name = ((char *) rw) + sizeof(RegisteredBgWorker);
5247 strlcpy(rw->rw_worker.bgw_name, worker->bgw_name, namelen + 1);
5249 rw->rw_backend = NULL;
5251 rw->rw_child_slot = 0;
5252 rw->rw_crashed_at = 0;
5254 rw->rw_cookie = BackgroundWorkerCookie++;
5257 slist_push_head(&BackgroundWorkerList, &rw->rw_lnode);
5261 * Connect background worker to a database.
5264 BackgroundWorkerInitializeConnection(char *dbname, char *username)
5266 BackgroundWorker *worker = MyBgworkerEntry;
5268 /* XXX is this the right errcode? */
5269 if (!(worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION))
5271 (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
5272 errmsg("database connection requirement not indicated during registration")));
5274 InitPostgres(dbname, InvalidOid, username, NULL);
5276 /* it had better not gotten out of "init" mode yet */
5277 if (!IsInitProcessingMode())
5279 (errmsg("invalid processing mode in bgworker")));
5280 SetProcessingMode(NormalProcessing);
5284 * Block/unblock signals in a background worker
5287 BackgroundWorkerBlockSignals(void)
5289 PG_SETMASK(&BlockSig);
5293 BackgroundWorkerUnblockSignals(void)
5295 PG_SETMASK(&UnBlockSig);
5299 static BackgroundWorker *
5300 find_bgworker_entry(int cookie)
5304 slist_foreach(iter, &BackgroundWorkerList)
5306 RegisteredBgWorker *rw;
5308 rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
5309 if (rw->rw_cookie == cookie)
5310 return &rw->rw_worker;
5318 bgworker_quickdie(SIGNAL_ARGS)
5320 sigaddset(&BlockSig, SIGQUIT); /* prevent nested calls */
5321 PG_SETMASK(&BlockSig);
5324 * We DO NOT want to run proc_exit() callbacks -- we're here because
5325 * shared memory may be corrupted, so we don't want to try to clean up our
5326 * transaction. Just nail the windows shut and get out of town. Now that
5327 * there's an atexit callback to prevent third-party code from breaking
5328 * things by calling exit() directly, we have to reset the callbacks
5329 * explicitly to make this work as intended.
5334 * Note we do exit(0) here, not exit(2) like quickdie. The reason is that
5335 * we don't want to be seen this worker as independently crashed, because
5336 * then postmaster would delay restarting it again afterwards. If some
5337 * idiot DBA manually sends SIGQUIT to a random bgworker, the "dead man
5338 * switch" will ensure that postmaster sees this as a crash.
5344 * Standard SIGTERM handler for background workers
5347 bgworker_die(SIGNAL_ARGS)
5349 PG_SETMASK(&BlockSig);
5352 (errcode(ERRCODE_ADMIN_SHUTDOWN),
5353 errmsg("terminating background worker \"%s\" due to administrator command",
5354 MyBgworkerEntry->bgw_name)));
5358 do_start_bgworker(void)
5360 sigjmp_buf local_sigjmp_buf;
5361 char buf[MAXPGPATH];
5362 BackgroundWorker *worker = MyBgworkerEntry;
5365 elog(FATAL, "unable to find bgworker entry");
5367 /* we are a postmaster subprocess now */
5368 IsUnderPostmaster = true;
5369 IsBackgroundWorker = true;
5371 /* reset MyProcPid */
5372 MyProcPid = getpid();
5374 /* record Start Time for logging */
5375 MyStartTime = time(NULL);
5377 /* Identify myself via ps */
5378 snprintf(buf, MAXPGPATH, "bgworker: %s", worker->bgw_name);
5379 init_ps_display(buf, "", "", "");
5381 SetProcessingMode(InitProcessing);
5383 /* Apply PostAuthDelay */
5384 if (PostAuthDelay > 0)
5385 pg_usleep(PostAuthDelay * 1000000L);
5388 * If possible, make this process a group leader, so that the postmaster
5389 * can signal any child processes too.
5393 elog(FATAL, "setsid() failed: %m");
5397 * Set up signal handlers.
5399 if (worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)
5402 * SIGINT is used to signal canceling the current action
5404 pqsignal(SIGINT, StatementCancelHandler);
5405 pqsignal(SIGUSR1, procsignal_sigusr1_handler);
5406 pqsignal(SIGFPE, FloatExceptionHandler);
5408 /* XXX Any other handlers needed here? */
5412 pqsignal(SIGINT, SIG_IGN);
5413 pqsignal(SIGUSR1, SIG_IGN);
5414 pqsignal(SIGFPE, SIG_IGN);
5417 /* SIGTERM and SIGHUP are configurable */
5418 if (worker->bgw_sigterm)
5419 pqsignal(SIGTERM, worker->bgw_sigterm);
5421 pqsignal(SIGTERM, bgworker_die);
5423 if (worker->bgw_sighup)
5424 pqsignal(SIGHUP, worker->bgw_sighup);
5426 pqsignal(SIGHUP, SIG_IGN);
5428 pqsignal(SIGQUIT, bgworker_quickdie);
5429 InitializeTimeouts(); /* establishes SIGALRM handler */
5431 pqsignal(SIGPIPE, SIG_IGN);
5432 pqsignal(SIGUSR2, SIG_IGN);
5433 pqsignal(SIGCHLD, SIG_DFL);
5436 * If an exception is encountered, processing resumes here.
5438 * See notes in postgres.c about the design of this coding.
5440 if (sigsetjmp(local_sigjmp_buf, 1) != 0)
5442 /* Since not using PG_TRY, must reset error stack by hand */
5443 error_context_stack = NULL;
5445 /* Prevent interrupts while cleaning up */
5448 /* Report the error to the server log */
5452 * Do we need more cleanup here? For shmem-connected bgworkers, we
5453 * will call InitProcess below, which will install ProcKill as exit
5454 * callback. That will take care of releasing locks, etc.
5461 /* We can now handle ereport(ERROR) */
5462 PG_exception_stack = &local_sigjmp_buf;
5464 /* Early initialization */
5468 * If necessary, create a per-backend PGPROC struct in shared memory,
5469 * except in the EXEC_BACKEND case where this was done in
5470 * SubPostmasterMain. We must do this before we can use LWLocks (and in
5471 * the EXEC_BACKEND case we already had to do some stuff with LWLocks).
5473 #ifndef EXEC_BACKEND
5474 if (worker->bgw_flags & BGWORKER_SHMEM_ACCESS)
5479 * Note that in normal processes, we would call InitPostgres here. For a
5480 * worker, however, we don't know what database to connect to, yet; so we
5481 * need to wait until the user code does it via
5482 * BackgroundWorkerInitializeConnection().
5486 * Now invoke the user-defined worker code
5488 worker->bgw_main(worker->bgw_main_arg);
5490 /* ... and if it returns, we're done */
5495 * Return the number of background workers registered that have at least
5496 * one of the passed flag bits set.
5499 GetNumRegisteredBackgroundWorkers(int flags)
5504 slist_foreach(iter, &BackgroundWorkerList)
5506 RegisteredBgWorker *rw;
5508 rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
5511 !(rw->rw_worker.bgw_flags & flags))
5521 * Return the number of bgworkers that need to have PGPROC entries.
5524 GetNumShmemAttachedBgworkers(void)
5526 return GetNumRegisteredBackgroundWorkers(BGWORKER_SHMEM_ACCESS);
5531 bgworker_forkexec(int cookie)
5535 char forkav[MAXPGPATH];
5537 snprintf(forkav, MAXPGPATH, "--forkbgworker=%d", cookie);
5539 av[ac++] = "postgres";
5541 av[ac++] = NULL; /* filled in by postmaster_forkexec */
5544 Assert(ac < lengthof(av));
5546 return postmaster_forkexec(ac, av);
5551 * Start a new bgworker.
5552 * Starting time conditions must have been checked already.
5554 * This code is heavily based on autovacuum.c, q.v.
5557 start_bgworker(RegisteredBgWorker *rw)
5562 (errmsg("starting background worker process \"%s\"",
5563 rw->rw_worker.bgw_name)));
5566 switch ((worker_pid = bgworker_forkexec(rw->rw_cookie)))
5568 switch ((worker_pid = fork_process()))
5573 (errmsg("could not fork worker process: %m")));
5576 #ifndef EXEC_BACKEND
5578 /* in postmaster child ... */
5579 /* Close the postmaster's sockets */
5580 ClosePostmasterPorts(false);
5582 /* Lose the postmaster's on-exit routines */
5585 /* Do NOT release postmaster's working memory context */
5587 MyBgworkerEntry = &rw->rw_worker;
5588 do_start_bgworker();
5592 rw->rw_pid = worker_pid;
5594 rw->rw_backend->pid = rw->rw_pid;
5599 * Does the current postmaster state require starting a worker with the
5600 * specified start_time?
5603 bgworker_should_start_now(BgWorkerStartTime start_time)
5607 case PM_NO_CHILDREN:
5608 case PM_WAIT_DEAD_END:
5611 case PM_WAIT_BACKENDS:
5612 case PM_WAIT_READONLY:
5613 case PM_WAIT_BACKUP:
5617 if (start_time == BgWorkerStart_RecoveryFinished)
5621 case PM_HOT_STANDBY:
5622 if (start_time == BgWorkerStart_ConsistentState)
5629 if (start_time == BgWorkerStart_PostmasterStart)
5639 * Allocate the Backend struct for a connected background worker, but don't
5640 * add it to the list of backends just yet.
5642 * Some info from the Backend is copied into the passed rw.
5645 assign_backendlist_entry(RegisteredBgWorker *rw)
5647 Backend *bn = malloc(sizeof(Backend));
5652 (errcode(ERRCODE_OUT_OF_MEMORY),
5653 errmsg("out of memory")));
5656 * The worker didn't really crash, but setting this nonzero makes
5657 * postmaster wait a bit before attempting to start it again; if it
5658 * tried again right away, most likely it'd find itself under the same
5661 rw->rw_crashed_at = GetCurrentTimestamp();
5666 * Compute the cancel key that will be assigned to this session. We
5667 * probably don't need cancel keys for background workers, but we'd better
5668 * have something random in the field to prevent unfriendly people from
5669 * sending cancels to them.
5671 MyCancelKey = PostmasterRandom();
5672 bn->cancel_key = MyCancelKey;
5674 bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
5675 bn->bkend_type = BACKEND_TYPE_BGWORKER;
5676 bn->dead_end = false;
5678 rw->rw_backend = bn;
5679 rw->rw_child_slot = bn->child_slot;
5685 * If the time is right, start one background worker.
5687 * As a side effect, the bgworker control variables are set or reset whenever
5688 * there are more workers to start after this one, and whenever the overall
5689 * system state requires it.
5692 StartOneBackgroundWorker(void)
5695 TimestampTz now = 0;
5699 StartWorkerNeeded = false;
5700 HaveCrashedWorker = false;
5701 return; /* not yet */
5704 HaveCrashedWorker = false;
5706 slist_foreach(iter, &BackgroundWorkerList)
5708 RegisteredBgWorker *rw;
5710 rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur);
5712 /* already running? */
5713 if (rw->rw_pid != 0)
5717 * If this worker has crashed previously, maybe it needs to be
5718 * restarted (unless on registration it specified it doesn't want to
5719 * be restarted at all). Check how long ago did a crash last happen.
5720 * If the last crash is too recent, don't start it right away; let it
5721 * be restarted once enough time has passed.
5723 if (rw->rw_crashed_at != 0)
5725 if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART)
5729 now = GetCurrentTimestamp();
5731 if (!TimestampDifferenceExceeds(rw->rw_crashed_at, now,
5732 rw->rw_worker.bgw_restart_time * 1000))
5734 HaveCrashedWorker = true;
5739 if (bgworker_should_start_now(rw->rw_worker.bgw_start_time))
5741 /* reset crash time before calling assign_backendlist_entry */
5742 rw->rw_crashed_at = 0;
5745 * If necessary, allocate and assign the Backend element. Note we
5746 * must do this before forking, so that we can handle out of
5749 * If not connected, we don't need a Backend element, but we still
5750 * need a PMChildSlot.
5752 if (rw->rw_worker.bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)
5754 if (!assign_backendlist_entry(rw))
5758 rw->rw_child_slot = MyPMChildSlot = AssignPostmasterChildSlot();
5760 start_bgworker(rw); /* sets rw->rw_pid */
5764 dlist_push_head(&BackendList, &rw->rw_backend->elem);
5766 ShmemBackendArrayAdd(rw->rw_backend);
5771 * Have ServerLoop call us again. Note that there might not
5772 * actually *be* another runnable worker, but we don't care all
5773 * that much; we will find out the next time we run.
5775 StartWorkerNeeded = true;
5780 /* no runnable worker found */
5781 StartWorkerNeeded = false;
5787 * The following need to be available to the save/restore_backend_variables
5788 * functions. They are marked NON_EXEC_STATIC in their home modules.
5790 extern slock_t *ShmemLock;
5791 extern LWLock *LWLockArray;
5792 extern slock_t *ProcStructLock;
5793 extern PGPROC *AuxiliaryProcs;
5794 extern PMSignalData *PMSignalState;
5795 extern pgsocket pgStatSock;
5796 extern pg_time_t first_syslogger_file_time;
5799 #define write_inheritable_socket(dest, src, childpid) ((*(dest) = (src)), true)
5800 #define read_inheritable_socket(dest, src) (*(dest) = *(src))
5802 static bool write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE child);
5803 static bool write_inheritable_socket(InheritableSocket *dest, SOCKET src,
5805 static void read_inheritable_socket(SOCKET *dest, InheritableSocket *src);
5809 /* Save critical backend variables into the BackendParameters struct */
5812 save_backend_variables(BackendParameters *param, Port *port)
5815 save_backend_variables(BackendParameters *param, Port *port,
5816 HANDLE childProcess, pid_t childPid)
5819 memcpy(¶m->port, port, sizeof(Port));
5820 if (!write_inheritable_socket(¶m->portsocket, port->sock, childPid))
5823 strlcpy(param->DataDir, DataDir, MAXPGPATH);
5825 memcpy(¶m->ListenSocket, &ListenSocket, sizeof(ListenSocket));
5827 param->MyCancelKey = MyCancelKey;
5828 param->MyPMChildSlot = MyPMChildSlot;
5830 param->UsedShmemSegID = UsedShmemSegID;
5831 param->UsedShmemSegAddr = UsedShmemSegAddr;
5833 param->ShmemLock = ShmemLock;
5834 param->ShmemVariableCache = ShmemVariableCache;
5835 param->ShmemBackendArray = ShmemBackendArray;
5837 param->LWLockArray = LWLockArray;
5838 param->ProcStructLock = ProcStructLock;
5839 param->ProcGlobal = ProcGlobal;
5840 param->AuxiliaryProcs = AuxiliaryProcs;
5841 param->PreparedXactProcs = PreparedXactProcs;
5842 param->PMSignalState = PMSignalState;
5843 if (!write_inheritable_socket(¶m->pgStatSock, pgStatSock, childPid))
5846 param->PostmasterPid = PostmasterPid;
5847 param->PgStartTime = PgStartTime;
5848 param->PgReloadTime = PgReloadTime;
5849 param->first_syslogger_file_time = first_syslogger_file_time;
5851 param->redirection_done = redirection_done;
5852 param->IsBinaryUpgrade = IsBinaryUpgrade;
5853 param->max_safe_fds = max_safe_fds;
5855 param->MaxBackends = MaxBackends;
5858 param->PostmasterHandle = PostmasterHandle;
5859 if (!write_duplicated_handle(¶m->initial_signal_pipe,
5860 pgwin32_create_signal_listener(childPid),
5864 memcpy(¶m->postmaster_alive_fds, &postmaster_alive_fds,
5865 sizeof(postmaster_alive_fds));
5868 memcpy(¶m->syslogPipe, &syslogPipe, sizeof(syslogPipe));
5870 strlcpy(param->my_exec_path, my_exec_path, MAXPGPATH);
5872 strlcpy(param->pkglib_path, pkglib_path, MAXPGPATH);
5874 strlcpy(param->ExtraOptions, ExtraOptions, MAXPGPATH);
5882 * Duplicate a handle for usage in a child process, and write the child
5883 * process instance of the handle to the parameter file.
5886 write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE childProcess)
5888 HANDLE hChild = INVALID_HANDLE_VALUE;
5890 if (!DuplicateHandle(GetCurrentProcess(),
5896 DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS))
5899 (errmsg_internal("could not duplicate handle to be written to backend parameter file: error code %lu",
5909 * Duplicate a socket for usage in a child process, and write the resulting
5910 * structure to the parameter file.
5911 * This is required because a number of LSPs (Layered Service Providers) very
5912 * common on Windows (antivirus, firewalls, download managers etc) break
5913 * straight socket inheritance.
5916 write_inheritable_socket(InheritableSocket *dest, SOCKET src, pid_t childpid)
5918 dest->origsocket = src;
5919 if (src != 0 && src != PGINVALID_SOCKET)
5922 if (WSADuplicateSocket(src, childpid, &dest->wsainfo) != 0)
5925 (errmsg("could not duplicate socket %d for use in backend: error code %d",
5926 (int) src, WSAGetLastError())));
5934 * Read a duplicate socket structure back, and get the socket descriptor.
5937 read_inheritable_socket(SOCKET *dest, InheritableSocket *src)
5941 if (src->origsocket == PGINVALID_SOCKET || src->origsocket == 0)
5943 /* Not a real socket! */
5944 *dest = src->origsocket;
5948 /* Actual socket, so create from structure */
5949 s = WSASocket(FROM_PROTOCOL_INFO,
5955 if (s == INVALID_SOCKET)
5957 write_stderr("could not create inherited socket: error code %d\n",
5964 * To make sure we don't get two references to the same socket, close
5965 * the original one. (This would happen when inheritance actually
5968 closesocket(src->origsocket);
5974 read_backend_variables(char *id, Port *port)
5976 BackendParameters param;
5979 /* Non-win32 implementation reads from file */
5983 fp = AllocateFile(id, PG_BINARY_R);
5986 write_stderr("could not read from backend variables file \"%s\": %s\n",
5987 id, strerror(errno));
5991 if (fread(¶m, sizeof(param), 1, fp) != 1)
5993 write_stderr("could not read from backend variables file \"%s\": %s\n",
5994 id, strerror(errno));
6000 if (unlink(id) != 0)
6002 write_stderr("could not remove file \"%s\": %s\n",
6003 id, strerror(errno));
6007 /* Win32 version uses mapped file */
6009 BackendParameters *paramp;
6012 paramHandle = (HANDLE) _atoi64(id);
6014 paramHandle = (HANDLE) atol(id);
6016 paramp = MapViewOfFile(paramHandle, FILE_MAP_READ, 0, 0, 0);
6019 write_stderr("could not map view of backend variables: error code %lu\n",
6024 memcpy(¶m, paramp, sizeof(BackendParameters));
6026 if (!UnmapViewOfFile(paramp))
6028 write_stderr("could not unmap view of backend variables: error code %lu\n",
6033 if (!CloseHandle(paramHandle))
6035 write_stderr("could not close handle to backend parameter variables: error code %lu\n",
6041 restore_backend_variables(¶m, port);
6044 /* Restore critical backend variables from the BackendParameters struct */
6046 restore_backend_variables(BackendParameters *param, Port *port)
6048 memcpy(port, ¶m->port, sizeof(Port));
6049 read_inheritable_socket(&port->sock, ¶m->portsocket);
6051 SetDataDir(param->DataDir);
6053 memcpy(&ListenSocket, ¶m->ListenSocket, sizeof(ListenSocket));
6055 MyCancelKey = param->MyCancelKey;
6056 MyPMChildSlot = param->MyPMChildSlot;
6058 UsedShmemSegID = param->UsedShmemSegID;
6059 UsedShmemSegAddr = param->UsedShmemSegAddr;
6061 ShmemLock = param->ShmemLock;
6062 ShmemVariableCache = param->ShmemVariableCache;
6063 ShmemBackendArray = param->ShmemBackendArray;
6065 LWLockArray = param->LWLockArray;
6066 ProcStructLock = param->ProcStructLock;
6067 ProcGlobal = param->ProcGlobal;
6068 AuxiliaryProcs = param->AuxiliaryProcs;
6069 PreparedXactProcs = param->PreparedXactProcs;
6070 PMSignalState = param->PMSignalState;
6071 read_inheritable_socket(&pgStatSock, ¶m->pgStatSock);
6073 PostmasterPid = param->PostmasterPid;
6074 PgStartTime = param->PgStartTime;
6075 PgReloadTime = param->PgReloadTime;
6076 first_syslogger_file_time = param->first_syslogger_file_time;
6078 redirection_done = param->redirection_done;
6079 IsBinaryUpgrade = param->IsBinaryUpgrade;
6080 max_safe_fds = param->max_safe_fds;
6082 MaxBackends = param->MaxBackends;
6085 PostmasterHandle = param->PostmasterHandle;
6086 pgwin32_initial_signal_pipe = param->initial_signal_pipe;
6088 memcpy(&postmaster_alive_fds, ¶m->postmaster_alive_fds,
6089 sizeof(postmaster_alive_fds));
6092 memcpy(&syslogPipe, ¶m->syslogPipe, sizeof(syslogPipe));
6094 strlcpy(my_exec_path, param->my_exec_path, MAXPGPATH);
6096 strlcpy(pkglib_path, param->pkglib_path, MAXPGPATH);
6098 strlcpy(ExtraOptions, param->ExtraOptions, MAXPGPATH);
6103 ShmemBackendArraySize(void)
6105 return mul_size(MaxLivePostmasterChildren(), sizeof(Backend));
6109 ShmemBackendArrayAllocation(void)
6111 Size size = ShmemBackendArraySize();
6113 ShmemBackendArray = (Backend *) ShmemAlloc(size);
6114 /* Mark all slots as empty */
6115 memset(ShmemBackendArray, 0, size);
6119 ShmemBackendArrayAdd(Backend *bn)
6121 /* The array slot corresponding to my PMChildSlot should be free */
6122 int i = bn->child_slot - 1;
6124 Assert(ShmemBackendArray[i].pid == 0);
6125 ShmemBackendArray[i] = *bn;
6129 ShmemBackendArrayRemove(Backend *bn)
6131 int i = bn->child_slot - 1;
6133 Assert(ShmemBackendArray[i].pid == bn->pid);
6134 /* Mark the slot as empty */
6135 ShmemBackendArray[i].pid = 0;
6137 #endif /* EXEC_BACKEND */
6143 * Subset implementation of waitpid() for Windows. We assume pid is -1
6144 * (that is, check all child processes) and options is WNOHANG (don't wait).
6147 waitpid(pid_t pid, int *exitstatus, int options)
6154 * Check if there are any dead children. If there are, return the pid of
6155 * the first one that died.
6157 if (GetQueuedCompletionStatus(win32ChildQueue, &dwd, &key, &ovl, 0))
6159 *exitstatus = (int) key;
6167 * Note! Code below executes on a thread pool! All operations must
6168 * be thread safe! Note that elog() and friends must *not* be used.
6171 pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired)
6173 win32_deadchild_waitinfo *childinfo = (win32_deadchild_waitinfo *) lpParameter;
6176 if (TimerOrWaitFired)
6177 return; /* timeout. Should never happen, since we use
6178 * INFINITE as timeout value. */
6181 * Remove handle from wait - required even though it's set to wait only
6184 UnregisterWaitEx(childinfo->waitHandle, NULL);
6186 if (!GetExitCodeProcess(childinfo->procHandle, &exitcode))
6189 * Should never happen. Inform user and set a fixed exitcode.
6191 write_stderr("could not read exit code for process\n");
6195 if (!PostQueuedCompletionStatus(win32ChildQueue, childinfo->procId, (ULONG_PTR) exitcode, NULL))
6196 write_stderr("could not post child completion status\n");
6199 * Handle is per-process, so we close it here instead of in the
6200 * originating thread
6202 CloseHandle(childinfo->procHandle);
6205 * Free struct that was allocated before the call to
6206 * RegisterWaitForSingleObject()
6210 /* Queue SIGCHLD signal */
6211 pg_queue_signal(SIGCHLD);
6216 * Initialize one and only handle for monitoring postmaster death.
6218 * Called once in the postmaster, so that child processes can subsequently
6219 * monitor if their parent is dead.
6222 InitPostmasterDeathWatchHandle(void)
6227 * Create a pipe. Postmaster holds the write end of the pipe open
6228 * (POSTMASTER_FD_OWN), and children hold the read end. Children can pass
6229 * the read file descriptor to select() to wake up in case postmaster
6230 * dies, or check for postmaster death with a (read() == 0). Children must
6231 * close the write end as soon as possible after forking, because EOF
6232 * won't be signaled in the read end until all processes have closed the
6233 * write fd. That is taken care of in ClosePostmasterPorts().
6235 Assert(MyProcPid == PostmasterPid);
6236 if (pipe(postmaster_alive_fds))
6238 (errcode_for_file_access(),
6239 errmsg_internal("could not create pipe to monitor postmaster death: %m")));
6242 * Set O_NONBLOCK to allow testing for the fd's presence with a read()
6245 if (fcntl(postmaster_alive_fds[POSTMASTER_FD_WATCH], F_SETFL, O_NONBLOCK))
6247 (errcode_for_socket_access(),
6248 errmsg_internal("could not set postmaster death monitoring pipe to non-blocking mode: %m")));
6252 * On Windows, we use a process handle for the same purpose.
6254 if (DuplicateHandle(GetCurrentProcess(),
6255 GetCurrentProcess(),
6256 GetCurrentProcess(),
6260 DUPLICATE_SAME_ACCESS) == 0)
6262 (errmsg_internal("could not duplicate postmaster handle: error code %lu",
projects / postgresql / blob