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Commit723d018

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Use a latch to make startup process wake up and replay immediately when
new WAL arrives via streaming replication. This reduces the latency, andalso allows us to use a longer polling interval, which is good for energyefficiency.We still need to poll to check for the appearance of a trigger file, butthe interval is now 5 seconds (instead of 100ms), like when waiting fora new WAL segment to appear in WAL archive.
1 parent236b6bc commit723d018

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3 files changed

+53
-8
lines changed

3 files changed

+53
-8
lines changed

‎src/backend/access/transam/xlog.c

Lines changed: 47 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.434 2010/08/30 15:37:41 sriggs Exp $
10+
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.435 2010/09/15 10:35:05 heikki Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -46,6 +46,7 @@
4646
#include"storage/bufmgr.h"
4747
#include"storage/fd.h"
4848
#include"storage/ipc.h"
49+
#include"storage/latch.h"
4950
#include"storage/pmsignal.h"
5051
#include"storage/procarray.h"
5152
#include"storage/smgr.h"
@@ -392,6 +393,13 @@ typedef struct XLogCtlData
392393
*/
393394
boolSharedRecoveryInProgress;
394395

396+
/*
397+
* recoveryWakeupLatch is used to wake up the startup process to
398+
* continue WAL replay, if it is waiting for WAL to arrive or failover
399+
* trigger file to appear.
400+
*/
401+
LatchrecoveryWakeupLatch;
402+
395403
/*
396404
* During recovery, we keep a copy of the latest checkpoint record here.
397405
* Used by the background writer when it wants to create a restartpoint.
@@ -4840,6 +4848,7 @@ XLOGShmemInit(void)
48404848
XLogCtl->SharedRecoveryInProgress= true;
48414849
XLogCtl->Insert.currpage= (XLogPageHeader) (XLogCtl->pages);
48424850
SpinLockInit(&XLogCtl->info_lck);
4851+
InitSharedLatch(&XLogCtl->recoveryWakeupLatch);
48434852

48444853
/*
48454854
* If we are not in bootstrap mode, pg_control should already exist. Read
@@ -5814,6 +5823,13 @@ StartupXLOG(void)
58145823
(errmsg("starting archive recovery")));
58155824
}
58165825

5826+
/*
5827+
* Take ownership of the wakup latch if we're going to sleep during
5828+
* recovery.
5829+
*/
5830+
if (StandbyMode)
5831+
OwnLatch(&XLogCtl->recoveryWakeupLatch);
5832+
58175833
if (read_backup_label(&checkPointLoc))
58185834
{
58195835
/*
@@ -6274,6 +6290,13 @@ StartupXLOG(void)
62746290
if (WalRcvInProgress())
62756291
elog(PANIC,"wal receiver still active");
62766292

6293+
/*
6294+
* We don't need the latch anymore. It's not strictly necessary to disown
6295+
* it, but let's do it for the sake of tidyness.
6296+
*/
6297+
if (StandbyMode)
6298+
DisownLatch(&XLogCtl->recoveryWakeupLatch);
6299+
62776300
/*
62786301
* We are now done reading the xlog from stream. Turn off streaming
62796302
* recovery to force fetching the files (which would be required at end of
@@ -9139,6 +9162,13 @@ startupproc_quickdie(SIGNAL_ARGS)
91399162
}
91409163

91419164

9165+
/* SIGUSR1: let latch facility handle the signal */
9166+
staticvoid
9167+
StartupProcSigUsr1Handler(SIGNAL_ARGS)
9168+
{
9169+
latch_sigusr1_handler();
9170+
}
9171+
91429172
/* SIGHUP: set flag to re-read config file at next convenient time */
91439173
staticvoid
91449174
StartupProcSigHupHandler(SIGNAL_ARGS)
@@ -9213,7 +9243,7 @@ StartupProcessMain(void)
92139243
else
92149244
pqsignal(SIGALRM,SIG_IGN);
92159245
pqsignal(SIGPIPE,SIG_IGN);
9216-
pqsignal(SIGUSR1,SIG_IGN);
9246+
pqsignal(SIGUSR1,StartupProcSigUsr1Handler);
92179247
pqsignal(SIGUSR2,SIG_IGN);
92189248

92199249
/*
@@ -9397,16 +9427,17 @@ XLogPageRead(XLogRecPtr *RecPtr, int emode, bool fetching_ckpt,
93979427
}
93989428

93999429
/*
9400-
* Data not here yet, so check for trigger then sleep.
9430+
* Data not here yet, so check for trigger then sleep for
9431+
* five seconds like in the WAL file polling case below.
94019432
*/
94029433
if (CheckForStandbyTrigger())
94039434
gototriggered;
94049435

94059436
/*
9406-
* When streaming is active, we want to react quickly when
9407-
* the next WAL record arrives, so sleep only a bit.
9437+
* Wait for more WAL to arrive, or timeout to be reached
94089438
*/
9409-
pg_usleep(100000L);/* 100ms */
9439+
WaitLatch(&XLogCtl->recoveryWakeupLatch,5000000L);
9440+
ResetLatch(&XLogCtl->recoveryWakeupLatch);
94109441
}
94119442
else
94129443
{
@@ -9681,3 +9712,13 @@ CheckForStandbyTrigger(void)
96819712
}
96829713
return false;
96839714
}
9715+
9716+
/*
9717+
* Wake up startup process to replay newly arrived WAL, or to notice that
9718+
* failover has been requested.
9719+
*/
9720+
void
9721+
WakeupRecovery(void)
9722+
{
9723+
SetLatch(&XLogCtl->recoveryWakeupLatch);
9724+
}

‎src/backend/replication/walreceiver.c

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -29,7 +29,7 @@
2929
*
3030
*
3131
* IDENTIFICATION
32-
* $PostgreSQL: pgsql/src/backend/replication/walreceiver.c,v 1.16 2010/07/06 19:18:57 momjian Exp $
32+
* $PostgreSQL: pgsql/src/backend/replication/walreceiver.c,v 1.17 2010/09/15 10:35:05 heikki Exp $
3333
*
3434
*-------------------------------------------------------------------------
3535
*/
@@ -529,6 +529,9 @@ XLogWalRcvFlush(void)
529529
walrcv->receivedUpto=LogstreamResult.Flush;
530530
SpinLockRelease(&walrcv->mutex);
531531

532+
/* Signal the startup process that new WAL has arrived */
533+
WakeupRecovery();
534+
532535
/* Report XLOG streaming progress in PS display */
533536
if (update_process_title)
534537
{

‎src/include/access/xlog.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.116 2010/08/12 23:24:54 rhaas Exp $
9+
* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.117 2010/09/15 10:35:05 heikki Exp $
1010
*/
1111
#ifndefXLOG_H
1212
#defineXLOG_H
@@ -303,5 +303,6 @@ extern TimeLineID GetRecoveryTargetTLI(void);
303303

304304
externvoidHandleStartupProcInterrupts(void);
305305
externvoidStartupProcessMain(void);
306+
externvoidWakeupRecovery(void);
306307

307308
#endif/* XLOG_H */

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