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authorHeikki Linnakangas <heikki.linnakangas@iki.fi>2010-09-15 10:35:05 +0000
committerHeikki Linnakangas <heikki.linnakangas@iki.fi>2010-09-15 10:35:05 +0000
commit723d0184e2972f21db0f85feef3d35f0cb9b3298 (patch)
tree0fc71e9bb51fc6f347f7ec630c71e3362d8e496d /src
parent236b6bc29e532822a366b56404ecaf1d906229bf (diff)
downloadpostgresql-723d0184e2972f21db0f85feef3d35f0cb9b3298.tar.gz
postgresql-723d0184e2972f21db0f85feef3d35f0cb9b3298.zip
Use a latch to make startup process wake up and replay immediately when
new WAL arrives via streaming replication. This reduces the latency, and also allows us to use a longer polling interval, which is good for energy efficiency. We still need to poll to check for the appearance of a trigger file, but the interval is now 5 seconds (instead of 100ms), like when waiting for a new WAL segment to appear in WAL archive.
Diffstat (limited to 'src')
-rw-r--r--src/backend/access/transam/xlog.c53
-rw-r--r--src/backend/replication/walreceiver.c5
-rw-r--r--src/include/access/xlog.h3
3 files changed, 53 insertions, 8 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index d2d1e9ad5a1..7135196b224 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.434 2010/08/30 15:37:41 sriggs Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.435 2010/09/15 10:35:05 heikki Exp $
*
*-------------------------------------------------------------------------
*/
@@ -46,6 +46,7 @@
#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "storage/ipc.h"
+#include "storage/latch.h"
#include "storage/pmsignal.h"
#include "storage/procarray.h"
#include "storage/smgr.h"
@@ -393,6 +394,13 @@ typedef struct XLogCtlData
bool SharedRecoveryInProgress;
/*
+ * recoveryWakeupLatch is used to wake up the startup process to
+ * continue WAL replay, if it is waiting for WAL to arrive or failover
+ * trigger file to appear.
+ */
+ Latch recoveryWakeupLatch;
+
+ /*
* During recovery, we keep a copy of the latest checkpoint record here.
* Used by the background writer when it wants to create a restartpoint.
*
@@ -4840,6 +4848,7 @@ XLOGShmemInit(void)
XLogCtl->SharedRecoveryInProgress = true;
XLogCtl->Insert.currpage = (XLogPageHeader) (XLogCtl->pages);
SpinLockInit(&XLogCtl->info_lck);
+ InitSharedLatch(&XLogCtl->recoveryWakeupLatch);
/*
* If we are not in bootstrap mode, pg_control should already exist. Read
@@ -5814,6 +5823,13 @@ StartupXLOG(void)
(errmsg("starting archive recovery")));
}
+ /*
+ * Take ownership of the wakup latch if we're going to sleep during
+ * recovery.
+ */
+ if (StandbyMode)
+ OwnLatch(&XLogCtl->recoveryWakeupLatch);
+
if (read_backup_label(&checkPointLoc))
{
/*
@@ -6275,6 +6291,13 @@ StartupXLOG(void)
elog(PANIC, "wal receiver still active");
/*
+ * We don't need the latch anymore. It's not strictly necessary to disown
+ * it, but let's do it for the sake of tidyness.
+ */
+ if (StandbyMode)
+ DisownLatch(&XLogCtl->recoveryWakeupLatch);
+
+ /*
* We are now done reading the xlog from stream. Turn off streaming
* recovery to force fetching the files (which would be required at end of
* recovery, e.g., timeline history file) from archive or pg_xlog.
@@ -9139,6 +9162,13 @@ startupproc_quickdie(SIGNAL_ARGS)
}
+/* SIGUSR1: let latch facility handle the signal */
+static void
+StartupProcSigUsr1Handler(SIGNAL_ARGS)
+{
+ latch_sigusr1_handler();
+}
+
/* SIGHUP: set flag to re-read config file at next convenient time */
static void
StartupProcSigHupHandler(SIGNAL_ARGS)
@@ -9213,7 +9243,7 @@ StartupProcessMain(void)
else
pqsignal(SIGALRM, SIG_IGN);
pqsignal(SIGPIPE, SIG_IGN);
- pqsignal(SIGUSR1, SIG_IGN);
+ pqsignal(SIGUSR1, StartupProcSigUsr1Handler);
pqsignal(SIGUSR2, SIG_IGN);
/*
@@ -9397,16 +9427,17 @@ retry:
}
/*
- * Data not here yet, so check for trigger then sleep.
+ * Data not here yet, so check for trigger then sleep for
+ * five seconds like in the WAL file polling case below.
*/
if (CheckForStandbyTrigger())
goto triggered;
/*
- * When streaming is active, we want to react quickly when
- * the next WAL record arrives, so sleep only a bit.
+ * Wait for more WAL to arrive, or timeout to be reached
*/
- pg_usleep(100000L); /* 100ms */
+ WaitLatch(&XLogCtl->recoveryWakeupLatch, 5000000L);
+ ResetLatch(&XLogCtl->recoveryWakeupLatch);
}
else
{
@@ -9681,3 +9712,13 @@ CheckForStandbyTrigger(void)
}
return false;
}
+
+/*
+ * Wake up startup process to replay newly arrived WAL, or to notice that
+ * failover has been requested.
+ */
+void
+WakeupRecovery(void)
+{
+ SetLatch(&XLogCtl->recoveryWakeupLatch);
+}
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 06646ead94a..ca5fddaee32 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -29,7 +29,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/replication/walreceiver.c,v 1.16 2010/07/06 19:18:57 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/replication/walreceiver.c,v 1.17 2010/09/15 10:35:05 heikki Exp $
*
*-------------------------------------------------------------------------
*/
@@ -529,6 +529,9 @@ XLogWalRcvFlush(void)
walrcv->receivedUpto = LogstreamResult.Flush;
SpinLockRelease(&walrcv->mutex);
+ /* Signal the startup process that new WAL has arrived */
+ WakeupRecovery();
+
/* Report XLOG streaming progress in PS display */
if (update_process_title)
{
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 3d8ffbba615..ea156d38345 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.116 2010/08/12 23:24:54 rhaas Exp $
+ * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.117 2010/09/15 10:35:05 heikki Exp $
*/
#ifndef XLOG_H
#define XLOG_H
@@ -303,5 +303,6 @@ extern TimeLineID GetRecoveryTargetTLI(void);
extern void HandleStartupProcInterrupts(void);
extern void StartupProcessMain(void);
+extern void WakeupRecovery(void);
#endif /* XLOG_H */