Add startup-time check that -B is not unreasonably small for

given number of backends (-N), per recent discussion in pghackers list.

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 46e224385ba1d8f028783acfd1cd6fe7cb919867..7a88385e49140b9ee7322bf9b6f04ae502880ff3 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 1.105 1999/05/25 16:10:40 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.106 1999/06/04 21:14:46 tgl Exp $
  *
  * NOTES
  *
@@ -427,7 +427,7 @@ PostmasterMain(int argc, char *argv[])
                 * means we have to start each backend with a -B # to make
                 * sure they know how many buffers were allocated.
                 */
-               NBuffers = atol(optarg);
+               NBuffers = atoi(optarg);
                strcat(ExtraOptions, " -B ");
                strcat(ExtraOptions, optarg);
                break;
@@ -530,9 +530,26 @@ PostmasterMain(int argc, char *argv[])
                break;
        }
    }
+
+   /*
+    * Select default values for switches where needed
+    */
    if (PostPortName == -1)
        PostPortName = pq_getport();
 
+   /*
+    * Check for invalid combinations of switches
+    */
+   if (NBuffers < 2 * MaxBackends || NBuffers < 16)
+   {
+       /* Do not accept -B so small that backends are likely to starve for
+        * lack of buffers.  The specific choices here are somewhat arbitrary.
+        */
+       fprintf(stderr, "%s: -B must be at least twice -N and at least 16.\n",
+               progname);
+       exit(1);
+   }
+
    checkDataDir(DataDir, &DataDirOK);  /* issues error messages */
    if (!DataDirOK)
    {