Administration
==============
-* -Allow administrators to safely terminate individual sessions either
+* Allow administrators to safely terminate individual sessions either
via an SQL function or SIGTERM
+
+ Lock table corruption following SIGTERM of an individual backend
+ has been reported in 8.0. A possible cause was fixed in 8.1, but
+ it is unknown whether other problems exist. This item mostly
+ requires additional testing rather than of writing any new code.
+
+ http://archives.postgresql.org/pgsql-hackers/2006-08/msg00174.php
+ http://archives.postgresql.org/pgsql-hackers/2007-04/msg00218.php
+
* Check for unreferenced table files created by transactions that were
in-progress when the server terminated abruptly
<h1><a name="section_2">Administration</a></h1>
<ul>
- <li>-<em>Allow administrators to safely terminate individual sessions either</em>
+ <li>Allow administrators to safely terminate individual sessions either
via an SQL function or SIGTERM
+<p> Lock table corruption following SIGTERM of an individual backend
+ has been reported in 8.0. A possible cause was fixed in 8.1, but
+ it is unknown whether other problems exist. This item mostly
+ requires additional testing rather than of writing any new code.
+</p>
+<p> <a href="http://archives.postgresql.org/pgsql-hackers/2006-08/msg00174.php">http://archives.postgresql.org/pgsql-hackers/2006-08/msg00174.php</a>
+ <a href="http://archives.postgresql.org/pgsql-hackers/2007-04/msg00218.php">http://archives.postgresql.org/pgsql-hackers/2007-04/msg00218.php</a>
+</p>
</li><li>Check for unreferenced table files created by transactions that were
in-progress when the server terminated abruptly
<p> <a href="http://archives.postgresql.org/pgsql-patches/2006-06/msg00096.php">http://archives.postgresql.org/pgsql-patches/2006-06/msg00096.php</a>
-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.431 2008/04/15 13:55:11 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.432 2008/04/15 20:28:46 momjian Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
<indexterm>
<primary>pg_cancel_backend</primary>
</indexterm>
- <indexterm>
- <primary>pg_terminate_backend</primary>
- </indexterm>
<indexterm>
<primary>pg_reload_conf</primary>
</indexterm>
<entry><type>boolean</type></entry>
<entry>Cancel a backend's current query</entry>
</row>
- <row>
- <entry>
- <literal><function>pg_terminate_backend</function>(<parameter>pid</parameter> <type>int</>)</literal>
- </entry>
- <entry><type>boolean</type></entry>
- <entry>Terminate a backend</entry>
- </row>
<row>
<entry>
<literal><function>pg_reload_conf</function>()</literal>
</para>
<para>
- <function>pg_cancel_backend</> and <function>pg_terminate_backend</>
- send a query cancel (<systemitem>SIGINT</>) signal to a backend process
- identified by process ID. The
- process ID of an active backend can be found from
+ <function>pg_cancel_backend</> sends a query cancel
+ (<systemitem>SIGINT</>) signal to a backend process identified by
+ process ID. The process ID of an active backend can be found from
the <structfield>procpid</structfield> column in the
<structname>pg_stat_activity</structname> view, or by listing the
<command>postgres</command> processes on the server with
-<!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.412 2008/04/15 13:55:11 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.413 2008/04/15 20:28:46 momjian Exp $ -->
<chapter Id="runtime">
<title>Operating System Environment</title>
well.
</para>
</important>
-
- <para>
- To terminate a session while allowing other sessions to continue, use
- <function>pg_terminate_backend()</> (<xref
- linkend="functions-admin-signal-table">) rather than sending a signal
- to the child process.
- </para>
</sect1>
<sect1 id="preventing-server-spoofing">
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.549 2008/04/15 13:55:11 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.550 2008/04/15 20:28:46 momjian Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
* waiting for input, however.
*/
if (ImmediateInterruptOK && InterruptHoldoffCount == 0 &&
- CritSectionCount == 0 &&
- (!DoingCommandRead || MyProc->terminate))
+ CritSectionCount == 0 && !DoingCommandRead)
{
/* bump holdoff count to make ProcessInterrupts() a no-op */
/* until we are done getting ready for it */
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
errmsg("canceling autovacuum task")));
- else if (MyProc->terminate)
- ereport(ERROR,
- (errcode(ERRCODE_ADMIN_SHUTDOWN),
- errmsg("terminating backend due to administrator command")));
else
ereport(ERROR,
(errcode(ERRCODE_QUERY_CANCELED),
/* We don't have a transaction command open anymore */
xact_started = false;
- if (MyProc->terminate)
- die(SIGINT);
-
/* Now we can allow interrupts again */
RESUME_INTERRUPTS();
}
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/misc.c,v 1.60 2008/04/15 13:55:11 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/misc.c,v 1.61 2008/04/15 20:28:46 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postmaster/syslogger.h"
#include "storage/fd.h"
#include "storage/pmsignal.h"
-#include "storage/proc.h"
#include "storage/procarray.h"
#include "utils/builtins.h"
#include "tcop/tcopprot.h"
* Functions to send signals to other backends.
*/
static bool
-pg_signal_check(int pid)
+pg_signal_backend(int pid, int sig)
{
if (!superuser())
ereport(ERROR,
(errmsg("PID %d is not a PostgreSQL server process", pid)));
return false;
}
- else
- return true;
-}
-/*
- * Functions to send signals to other backends.
- */
-static bool
-pg_signal_backend(int pid, int sig)
-{
/* If we have setsid(), signal the backend's whole process group */
#ifdef HAVE_SETSID
if (kill(-pid, sig))
Datum
pg_cancel_backend(PG_FUNCTION_ARGS)
{
- int pid = PG_GETARG_INT32(0);
-
- if (pg_signal_check(pid))
- PG_RETURN_BOOL(pg_signal_backend(pid, SIGINT));
- else
- PG_RETURN_BOOL(false);
-}
-
-/*
- * To cleanly terminate a backend, we set PGPROC(pid)->terminate
- * then send a cancel signal. We get ProcArrayLock only when
- * setting PGPROC->terminate so the function might fail in
- * several places, but that is fine because in those cases the
- * backend is already gone.
- */
-Datum
-pg_terminate_backend(PG_FUNCTION_ARGS)
-{
- int pid = PG_GETARG_INT32(0);
- volatile PGPROC *term_proc;
-
- /* Is this the super-user, and can we find the PGPROC entry for the pid? */
- if (pg_signal_check(pid) && (term_proc = BackendPidGetProc(pid)) != NULL)
- {
- LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
- /* Recheck now that we have the ProcArray lock. */
- if (term_proc->pid == pid)
- {
- term_proc->terminate = true;
- LWLockRelease(ProcArrayLock);
- PG_RETURN_BOOL(pg_signal_backend(pid, SIGINT));
- }
- else
- LWLockRelease(ProcArrayLock);
- }
-
- PG_RETURN_BOOL(false);
+ PG_RETURN_BOOL(pg_signal_backend(PG_GETARG_INT32(0), SIGINT));
}
Datum
PG_RETURN_BOOL(true);
}
+#ifdef NOT_USED
+
+/* Disabled in 8.0 due to reliability concerns; FIXME someday */
+Datum
+pg_terminate_backend(PG_FUNCTION_ARGS)
+{
+ PG_RETURN_INT32(pg_signal_backend(PG_GETARG_INT32(0), SIGTERM));
+}
+#endif
+
+
/* Function to find out which databases make use of a tablespace */
typedef struct
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.490 2008/04/15 13:55:11 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.491 2008/04/15 20:28:46 momjian Exp $
*
* NOTES
* The script catalog/genbki.sh reads this file and generates .bki
DATA(insert OID = 2171 ( pg_cancel_backend PGNSP PGUID 12 1 0 f f t f v 1 16 "23" _null_ _null_ _null_ pg_cancel_backend - _null_ _null_ ));
DESCR("cancel a server process' current query");
-DATA(insert OID = 2096 ( pg_terminate_backend PGNSP PGUID 12 1 0 f f t f v 1 16 "23" _null_ _null_ _null_ pg_terminate_backend - _null_ _null_ ));
-DESCR("terminate a server process");
DATA(insert OID = 2172 ( pg_start_backup PGNSP PGUID 12 1 0 f f t f v 1 25 "25" _null_ _null_ _null_ pg_start_backup - _null_ _null_ ));
DESCR("prepare for taking an online backup");
DATA(insert OID = 2173 ( pg_stop_backup PGNSP PGUID 12 1 0 f f t f v 0 25 "" _null_ _null_ _null_ pg_stop_backup - _null_ _null_ ));
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.105 2008/04/15 13:55:12 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.106 2008/04/15 20:28:47 momjian Exp $
*
*-------------------------------------------------------------------------
*/
bool inCommit; /* true if within commit critical section */
- bool terminate; /* admin requested termination */
-
uint8 vacuumFlags; /* vacuum-related flags, see above */
/* Info about LWLock the process is currently waiting for, if any. */
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.313 2008/04/15 13:55:12 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.314 2008/04/15 20:28:47 momjian Exp $
*
*-------------------------------------------------------------------------
*/
extern Datum current_database(PG_FUNCTION_ARGS);
extern Datum current_query(PG_FUNCTION_ARGS);
extern Datum pg_cancel_backend(PG_FUNCTION_ARGS);
-extern Datum pg_terminate_backend(PG_FUNCTION_ARGS);
extern Datum pg_reload_conf(PG_FUNCTION_ARGS);
extern Datum pg_tablespace_databases(PG_FUNCTION_ARGS);
extern Datum pg_rotate_logfile(PG_FUNCTION_ARGS);
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