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 46e2243..7a88385 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)
        {