Fix a thinko introduced into CountActiveBackends by a recent patch:

tglsfdc · tglsfdc · commit 850490579318 · 2009-07-29T15:57:11.000Z
we should ignore NULL array entries, not non-NULL ones.  This had the
effect of disabling commit_delay, and could have caused a crash in the
rare race condition the patch was intended to fix.

Bug report and diagnosis by Jeff Janes, in bug #4952.
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
@@ -23,7 +23,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.50 2009/06/11 14:49:02 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.51 2009/07/29 15:57:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1137,7 +1137,7 @@ CountActiveBackends(void)
 		 * free list and are recycled. Its contents are nonsense in that case,
 		 * but that's acceptable for this function.
 		 */
-		if (proc != NULL)
+		if (proc == NULL)
 			continue;
 
 		if (proc == MyProc)

Original file line number	Diff line number	Diff line change
`@@ -23,7 +23,7 @@`
`23`	`23`	`*`
`24`	`24`	`*`
`25`	`25`	`* IDENTIFICATION`
`26`		`- * $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.50 2009/06/11 14:49:02 momjian Exp $`
	`26`	`+ * $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.51 2009/07/29 15:57:11 tgl Exp $`
`27`	`27`	`*`
`28`	`28`	`*-------------------------------------------------------------------------`
`29`	`29`	`*/`
`@@ -1137,7 +1137,7 @@ CountActiveBackends(void)`
`1137`	`1137`	`* free list and are recycled. Its contents are nonsense in that case,`
`1138`	`1138`	`* but that's acceptable for this function.`
`1139`	`1139`	`*/`
`1140`		`- if (proc != NULL)`
	`1140`	`+ if (proc == NULL)`
`1141`	`1141`	`continue;`
`1142`	`1142`
`1143`	`1143`	`if (proc == MyProc)`