Fix postmaster to not try to start more than MaxBackendId children,

per patch from Tatsuo Ishii

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 795b1959fde8461d9e1d43c7f7db32e4c1c93de3..4ae3d7234ba1ccb3bf4c3b0f3e423164a0695d2f 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.99 1999/01/17 06:18:34 momjian Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.100 1999/01/30 20:04:37 tgl Exp $
  *
  * NOTES
  *
@@ -244,6 +244,7 @@ static int  initMasks(fd_set *rmask, fd_set *wmask);
 static long PostmasterRandom(void);
 static void RandomSalt(char *salt);
 static void SignalChildren(SIGNAL_ARGS);
+static int CountChildren(void);
 
 #ifdef CYR_RECODE
 void           GetCharSetByHost(char *, int, char *);
@@ -667,8 +668,8 @@ ServerLoop(void)
                {
                        if (errno == EINTR)
                                continue;
-                       fprintf(stderr, "%s: ServerLoop: select failed\n",
-                                       progname);
+                       fprintf(stderr, "%s: ServerLoop: select failed: %s\n",
+                                       progname, strerror(errno));
                        return STATUS_ERROR;
                }
 
@@ -763,19 +764,24 @@ ServerLoop(void)
 
                        if (status == STATUS_OK && port->pktInfo.state == Idle)
                        {
-
-                               /*
-                                * If the backend start fails then keep the connection
-                                * open to report it.  Otherwise, pretend there is an
-                                * error to close the connection which will now be managed
-                                * by the backend.
-                                */
-
-                               if (BackendStartup(port) != STATUS_OK)
+                               /* Can't start backend if max backend count is exceeded. */
+                               if (CountChildren() >= MaxBackendId)
                                        PacketSendError(&port->pktInfo,
-                                                                       "Backend startup failed");
+                                                                       "Sorry, too many clients already");
                                else
-                                       status = STATUS_ERROR;
+                               {
+                                       /*
+                                        * If the backend start fails then keep the connection
+                                        * open to report it.  Otherwise, pretend there is an
+                                        * error to close the connection which will now be managed
+                                        * by the backend.
+                                        */
+                                       if (BackendStartup(port) != STATUS_OK)
+                                               PacketSendError(&port->pktInfo,
+                                                                               "Backend startup failed");
+                                       else
+                                               status = STATUS_ERROR;
+                               }
                        }
 
                        /* Close the connection if required. */
@@ -1332,8 +1338,8 @@ BackendStartup(Port *port)
        /* in parent */
        if (pid < 0)
        {
-               fprintf(stderr, "%s: BackendStartup: fork failed\n",
-                               progname);
+               fprintf(stderr, "%s: BackendStartup: fork failed: %s\n",
+                               progname, strerror(errno));
                return STATUS_ERROR;
        }
 
@@ -1641,3 +1647,23 @@ PostmasterRandom(void)
 
        return random() ^ random_seed;
 }
+
+/*
+ * Count up number of child processes.
+ */
+static int
+CountChildren(void)
+{
+       Dlelem     *curr;
+       Backend    *bp;
+       int                     mypid = getpid();
+       int                     cnt = 0;
+
+       for (curr = DLGetHead(BackendList); curr; curr = DLGetSucc(curr))
+       {
+               bp = (Backend *) DLE_VAL(curr);
+               if (bp->pid != mypid)
+                       cnt++;
+       }
+       return cnt;
+}