Initialize SLRU stats entries to zero.

MasaoFujii · MasaoFujii · commit f3d23d83ef9a · 2020-05-13T22:19:25.000+09:00
Previously since SLRUStats was not initialized, SLRU stats counters could begin with non-zero value. Which could lead to incorrect results in pg_stat_slru view. Author: Fujii Masao Reviewed-by: Tomas Vondra Discussion: https://postgr.es/m/976bbb73-a112-de3c-c488-b34b64609793@oss.nttdata.com
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
@@ -2900,6 +2900,9 @@ pgstat_initialize(void)
 		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
 	}
 
+	/* Initialize SLRU statistics to zero */
+	memset(&SLRUStats, 0, sizeof(SLRUStats));
+
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
 }

Original file line number	Diff line number	Diff line change
`@@ -2900,6 +2900,9 @@ pgstat_initialize(void)`
`2900`	`2900`	`MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];`
`2901`	`2901`	`}`
`2902`	`2902`
	`2903`	`+ /* Initialize SLRU statistics to zero */`
	`2904`	`+ memset(&SLRUStats, 0, sizeof(SLRUStats));`
	`2905`	`+`
`2903`	`2906`	`/* Set up a process-exit hook to clean up */`
`2904`	`2907`	`on_shmem_exit(pgstat_beshutdown_hook, 0);`
`2905`	`2908`	`}`