Reduce CPU utilisation of WALSender process. Process was using 10% CPU

simonat2ndQuadrant · simonat2ndQuadrant · commit 08882ce74cd6 · 2010-03-24T20:11:12.000Z
doing nothing, caused by naptime specified in milliseconds yet units of
pg_usleep() parameter is microseconds. Correctly specifying units
reduces call frequency by 1000. Reduction in CPU consumption verified.
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
@@ -30,7 +30,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/replication/walsender.c,v 1.10 2010/03/16 09:09:55 heikki Exp $
+ *	  $PostgreSQL: pgsql/src/backend/replication/walsender.c,v 1.11 2010/03/24 20:11:12 sriggs Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -67,7 +67,7 @@ bool		am_walsender = false;		/* Am I a walsender process ? */
 int			MaxWalSenders = 0;	/* the maximum number of concurrent walsenders */
 int			WalSndDelay = 200;	/* max sleep time between some actions */
 
-#define NAPTIME_PER_CYCLE 100	/* max sleep time between cycles (100ms) */
+#define NAPTIME_PER_CYCLE 100000L	/* max sleep time between cycles (100ms) */
 
 /*
  * These variables are used similarly to openLogFile/Id/Seg/Off,
@@ -396,7 +396,7 @@ WalSndLoop(void)
 		 * sleep into NAPTIME_PER_CYCLE (ms) increments, and check for
 		 * interrupts after each nap.
 		 */
-		remain = WalSndDelay;
+		remain = WalSndDelay * 1000L;
 		while (remain > 0)
 		{
 			if (got_SIGHUP || shutdown_requested || ready_to_stop)

Original file line number	Diff line number	Diff line change
`@@ -30,7 +30,7 @@`
`30`	`30`	`*`
`31`	`31`	`*`
`32`	`32`	`* IDENTIFICATION`
`33`		`- * $PostgreSQL: pgsql/src/backend/replication/walsender.c,v 1.10 2010/03/16 09:09:55 heikki Exp $`
	`33`	`+ * $PostgreSQL: pgsql/src/backend/replication/walsender.c,v 1.11 2010/03/24 20:11:12 sriggs Exp $`
`34`	`34`	`*`
`35`	`35`	`*-------------------------------------------------------------------------`
`36`	`36`	`*/`
`@@ -67,7 +67,7 @@ bool am_walsender = false; /* Am I a walsender process ? */`
`67`	`67`	`int MaxWalSenders = 0; /* the maximum number of concurrent walsenders */`
`68`	`68`	`int WalSndDelay = 200; /* max sleep time between some actions */`
`69`	`69`
`70`		`-#define NAPTIME_PER_CYCLE 100 /* max sleep time between cycles (100ms) */`
	`70`	`+#define NAPTIME_PER_CYCLE 100000L /* max sleep time between cycles (100ms) */`
`71`	`71`
`72`	`72`	`/*`
`73`	`73`	`* These variables are used similarly to openLogFile/Id/Seg/Off,`
`@@ -396,7 +396,7 @@ WalSndLoop(void)`
`396`	`396`	`* sleep into NAPTIME_PER_CYCLE (ms) increments, and check for`
`397`	`397`	`* interrupts after each nap.`
`398`	`398`	`*/`
`399`		`- remain = WalSndDelay;`
	`399`	`+ remain = WalSndDelay * 1000L;`
`400`	`400`	`while (remain > 0)`
`401`	`401`	`{`
`402`	`402`	`if (got_SIGHUP \|\| shutdown_requested \|\| ready_to_stop)`