Attached is a patch that fixes these leaks, and does a couple other

things as well:
  * Computes and saves a cancel key for each backend.  * fflush
  before forking, to eliminate double-buffering problems
    between postmaster and backends.

Other cleanups.

Tom Lane

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 06ecedd21ebe032f0c558b99e6071fefb8cf0536..b657a2a64a6c05adde6567ffdc2518ea7845c5f8 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 1.84 1998/06/08 22:28:26 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.85 1998/06/09 04:06:12 momjian Exp $
  *
  * NOTES
  *
@@ -113,6 +113,7 @@
 typedef struct bkend
 {
    int         pid;            /* process id of backend */
+   long        cancel_key;     /* cancel key for cancels for this backend */
 } Backend;
 
 /* list of active backends.  For garbage collection only now. */
@@ -198,7 +199,14 @@ static sigset_t    oldsigmask,
 static int         orgsigmask = sigblock(0);
 #endif
 
+/*
+ * State for assigning random salts and cancel keys.
+ * Also, the global MyCancelKey passes the cancel key assigned to a given
+ * backend from the postmaster to that backend (via fork).
+ */
+
 static unsigned int random_seed = 0;
+long MyCancelKey = 0;
 
 extern char *optarg;
 extern int optind,
@@ -612,17 +620,22 @@ ServerLoop(void)
            return (STATUS_ERROR);
        }
 
-       if (random_seed == 0)
+       /*
+        * Select a random seed at the time of first receiving a request.
+        */
+       while (random_seed == 0)
        {
            gettimeofday(&later, &tz);
    
            /*
             *  We are not sure how much precision is in tv_usec, so we
-            *  swap the nibbles of 'later' and XOR them with 'now'
+            *  swap the nibbles of 'later' and XOR them with 'now'.
+            *  On the off chance that the result is 0, we loop until
+            *  it isn't.
             */
            random_seed = now.tv_usec ^
                    ((later.tv_usec << 16) |
-                   ((unsigned int)(later.tv_usec & 0xffff0000) >> 16));
+                   ((later.tv_usec >> 16) & 0xffff));
        }
                
        /*
@@ -1085,6 +1098,14 @@ BackendStartup(Port *port)
    }
 #endif
 
+   /*
+    * Compute the cancel key that will be assigned to this backend.
+    * The backend will have its own copy in the forked-off process'
+    * value of MyCancelKey, so that it can transmit the key to the
+    * frontend.
+    */
+   MyCancelKey = PostmasterRandom();
+
    if (DebugLvl > 2)
    {
        char      **p;
@@ -1098,17 +1119,21 @@ BackendStartup(Port *port)
        fprintf(stderr, "-----------------------------------------\n");
    }
 
+   /* Flush all stdio channels just before fork,
+    * to avoid double-output problems.
+    */
+   fflush(NULL);
+
     if ((pid = fork()) == 0)
    {  /* child */
         if (DoBackend(port))
        {
             fprintf(stderr, "%s child[%d]: BackendStartup: backend startup failed\n",
-                    progname, pid);
-           /* use _exit to keep from double-flushing stdio */
-           _exit(1);
+                    progname, (int) getpid());
+           exit(1);
        }
        else
-           _exit(0);
+           exit(0);
    }
 
    /* in parent */
@@ -1140,6 +1165,7 @@ BackendStartup(Port *port)
    }
 
    bn->pid = pid;
+   bn->cancel_key = MyCancelKey;
    DLAddHead(BackendList, DLNewElem(bn));
 
    ActiveBackends = TRUE;