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;
+}