Use WaitLatch() instead of pg_usleep() at the end of backups

michaelpq · michaelpq · commit 2aca19f2989a · 2021-07-06T08:10:59.000+09:00
This concerns pg_stop_backup() and BASE_BACKUP, when waiting for the WAL segments required for a backup to be archived. This simplifies a bit the handling of the wait event used in this code path. Author: Bharath Rupireddy Reviewed-by: Michael Paquier, Stephen Frost Discussion: https://postgr.es/m/CALj2ACU4AdPCq6NLfcA-ZGwX7pPCK5FgEj-CAU0xCKzkASSy_A@mail.gmail.com
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
@@ -11638,9 +11638,11 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 				reported_waiting = true;
 			}
 
-			pgstat_report_wait_start(WAIT_EVENT_BACKUP_WAIT_WAL_ARCHIVE);
-			pg_usleep(1000000L);
-			pgstat_report_wait_end();
+			(void) WaitLatch(MyLatch,
+							 WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
+							 1000L,
+							 WAIT_EVENT_BACKUP_WAIT_WAL_ARCHIVE);
+			ResetLatch(MyLatch);
 
 			if (++waits >= seconds_before_warning)
 			{

Original file line number	Diff line number	Diff line change
`@@ -11638,9 +11638,11 @@ do_pg_stop_backup(char labelfile, bool waitforarchive, TimeLineID stoptli_p)`
`11638`	`11638`	`reported_waiting = true;`
`11639`	`11639`	`}`
`11640`	`11640`
`11641`		`- pgstat_report_wait_start(WAIT_EVENT_BACKUP_WAIT_WAL_ARCHIVE);`
`11642`		`- pg_usleep(1000000L);`
`11643`		`- pgstat_report_wait_end();`
	`11641`	`+ (void) WaitLatch(MyLatch,`
	`11642`	`+ WL_LATCH_SET \| WL_TIMEOUT \| WL_EXIT_ON_PM_DEATH,`
	`11643`	`+ 1000L,`
	`11644`	`+ WAIT_EVENT_BACKUP_WAIT_WAL_ARCHIVE);`
	`11645`	`+ ResetLatch(MyLatch);`
`11644`	`11646`
`11645`	`11647`	`if (++waits >= seconds_before_warning)`
`11646`	`11648`	`{`