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Commit5a38af7

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Rearrange XLogFileInit so that control-file spinlock is not held while filling
the new log file with zeroes, only while renaming it into place. This shouldprevent problems with 'stuck spinlock' errors under heavy load.
1 parent5dc0e67 commit5a38af7

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1 file changed

+117
-75
lines changed
  • src/backend/access/transam

1 file changed

+117
-75
lines changed

‎src/backend/access/transam/xlog.c

Lines changed: 117 additions & 75 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.59 2001/03/16 05:44:33 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.60 2001/03/17 20:54:13 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -86,7 +86,7 @@
8686
/* Max time to wait to acquire XLog activity locks */
8787
#defineXLOG_LOCK_TIMEOUT(5*60*1000000)/* 5 minutes */
8888
/* Max time to wait to acquire checkpoint lock */
89-
#defineCHECKPOINT_LOCK_TIMEOUT(10*60*1000000)/*10 minutes */
89+
#defineCHECKPOINT_LOCK_TIMEOUT(20*60*1000000)/*20 minutes */
9090

9191
/* User-settable parameters */
9292
intCheckPointSegments=3;
@@ -335,10 +335,6 @@ static ControlFileData *ControlFile = NULL;
335335
snprintf(path, MAXPGPATH, "%s%c%08X%08X",\
336336
XLogDir, SEP_CHAR, log, seg)
337337

338-
#defineXLogTempFileName(path,log,seg)\
339-
snprintf(path, MAXPGPATH, "%s%cT%08X%08X",\
340-
XLogDir, SEP_CHAR, log, seg)
341-
342338
#definePrevBufIdx(idx)\
343339
(((idx) == 0) ? XLogCtl->XLogCacheBlck : ((idx) - 1))
344340

@@ -401,7 +397,8 @@ static bool InRedo = false;
401397

402398
staticboolAdvanceXLInsertBuffer(void);
403399
staticvoidXLogWrite(XLogwrtRqstWriteRqst);
404-
staticintXLogFileInit(uint32log,uint32seg,bool*usexistent);
400+
staticintXLogFileInit(uint32log,uint32seg,
401+
bool*use_existent,booluse_lock);
405402
staticintXLogFileOpen(uint32log,uint32seg,boolecont);
406403
staticvoidPreallocXlogFiles(XLogRecPtrendptr);
407404
staticvoidMoveOfflineLogs(uint32log,uint32seg);
@@ -960,7 +957,7 @@ XLogWrite(XLogwrtRqst WriteRqst)
960957
XLogCtlWrite*Write=&XLogCtl->Write;
961958
char*from;
962959
boolispartialpage;
963-
boolusexistent;
960+
booluse_existent;
964961

965962
/* Update local LogwrtResult (caller probably did this already, but...) */
966963
LogwrtResult=Write->LogwrtResult;
@@ -994,41 +991,42 @@ XLogWrite(XLogwrtRqst WriteRqst)
994991
}
995992
XLByteToPrevSeg(LogwrtResult.Write,openLogId,openLogSeg);
996993

997-
/* create/use new log file; need lock in case creating */
998-
SpinAcquire(ControlFileLockId);
999-
usexistent=true;
1000-
openLogFile=XLogFileInit(openLogId,openLogSeg,&usexistent);
994+
/* create/use new log file */
995+
use_existent= true;
996+
openLogFile=XLogFileInit(openLogId,openLogSeg,
997+
&use_existent, true);
1001998
openLogOff=0;
999+
1000+
if (!use_existent)/* there was no precreated file */
1001+
elog(LOG,"XLogWrite: new log file created - "
1002+
"consider increasing WAL_FILES");
1003+
10021004
/* update pg_control, unless someone else already did */
1005+
SpinAcquire(ControlFileLockId);
10031006
if (ControlFile->logId!=openLogId||
10041007
ControlFile->logSeg!=openLogSeg+1)
10051008
{
10061009
ControlFile->logId=openLogId;
10071010
ControlFile->logSeg=openLogSeg+1;
10081011
ControlFile->time=time(NULL);
10091012
UpdateControlFile();
1013+
/*
1014+
* Signal postmaster to start a checkpoint if it's been too
1015+
* long since the last one. (We look at local copy of
1016+
* RedoRecPtr which might be a little out of date, but should
1017+
* be close enough for this purpose.)
1018+
*/
1019+
if (IsUnderPostmaster&&
1020+
(openLogId!=RedoRecPtr.xlogid||
1021+
openLogSeg >= (RedoRecPtr.xrecoff /XLogSegSize)+
1022+
(uint32)CheckPointSegments))
1023+
{
1024+
if (XLOG_DEBUG)
1025+
fprintf(stderr,"XLogWrite: time for a checkpoint, signaling postmaster\n");
1026+
kill(getppid(),SIGUSR1);
1027+
}
10101028
}
10111029
SpinRelease(ControlFileLockId);
1012-
1013-
if (!usexistent)/* there was no precreated file */
1014-
elog(LOG,"XLogWrite: new log file created - "
1015-
"consider increasing WAL_FILES");
1016-
1017-
/*
1018-
* Signal postmaster to start a checkpoint if it's been too
1019-
* long since the last one. (We look at local copy of RedoRecPtr
1020-
* which might be a little out of date, but should be close enough
1021-
* for this purpose.)
1022-
*/
1023-
if (IsUnderPostmaster&&
1024-
(openLogId!=RedoRecPtr.xlogid||
1025-
openLogSeg >= (RedoRecPtr.xrecoff /XLogSegSize)+
1026-
(uint32)CheckPointSegments))
1027-
{
1028-
if (XLOG_DEBUG)
1029-
fprintf(stderr,"XLogWrite: time for a checkpoint, signaling postmaster\n");
1030-
kill(getppid(),SIGUSR1);
1031-
}
10321030
}
10331031

10341032
if (openLogFile<0)
@@ -1230,14 +1228,28 @@ XLogFlush(XLogRecPtr record)
12301228
/*
12311229
* Create a new XLOG file segment, or open a pre-existing one.
12321230
*
1231+
* log, seg: identify segment to be created/opened.
1232+
*
1233+
* *use_existent: if TRUE, OK to use a pre-existing file (else, any
1234+
* pre-existing file will be deleted). On return, TRUE if a pre-existing
1235+
* file was used.
1236+
*
1237+
* use_lock: if TRUE, acquire ControlFileLock spinlock while moving file into
1238+
* place. This should be TRUE except during bootstrap log creation. The
1239+
* caller must *not* hold the spinlock at call.
1240+
*
12331241
* Returns FD of opened file.
12341242
*/
12351243
staticint
1236-
XLogFileInit(uint32log,uint32seg,bool*usexistent)
1244+
XLogFileInit(uint32log,uint32seg,
1245+
bool*use_existent,booluse_lock)
12371246
{
12381247
charpath[MAXPGPATH];
1239-
chartpath[MAXPGPATH];
1248+
chartmppath[MAXPGPATH];
1249+
chartargpath[MAXPGPATH];
12401250
charzbuffer[BLCKSZ];
1251+
uint32targlog,
1252+
targseg;
12411253
intfd;
12421254
intnbytes;
12431255

@@ -1246,7 +1258,7 @@ XLogFileInit(uint32 log, uint32 seg, bool *usexistent)
12461258
/*
12471259
* Try to use existent file (checkpoint maker may have created it already)
12481260
*/
1249-
if (*usexistent)
1261+
if (*use_existent)
12501262
{
12511263
fd=BasicOpenFile(path,O_RDWR |PG_BINARY |XLOG_SYNC_BIT,
12521264
S_IRUSR |S_IWUSR);
@@ -1258,20 +1270,24 @@ XLogFileInit(uint32 log, uint32 seg, bool *usexistent)
12581270
}
12591271
else
12601272
return(fd);
1261-
/* Set flag to tell caller there was no existent file */
1262-
*usexistent= false;
12631273
}
12641274

1265-
XLogTempFileName(tpath,log,seg);
1266-
unlink(tpath);
1267-
unlink(path);
1275+
/*
1276+
* Initialize an empty (all zeroes) segment. NOTE: it is possible that
1277+
* another process is doing the same thing. If so, we will end up
1278+
* pre-creating an extra log segment. That seems OK, and better than
1279+
* holding the spinlock throughout this lengthy process.
1280+
*/
1281+
snprintf(tmppath,MAXPGPATH,"%s%cxlogtemp.%d",
1282+
XLogDir,SEP_CHAR, (int)getpid());
1283+
1284+
unlink(tmppath);
12681285

12691286
/* do not use XLOG_SYNC_BIT here --- want to fsync only at end of fill */
1270-
fd=BasicOpenFile(tpath,O_RDWR |O_CREAT |O_EXCL |PG_BINARY,
1287+
fd=BasicOpenFile(tmppath,O_RDWR |O_CREAT |O_EXCL |PG_BINARY,
12711288
S_IRUSR |S_IWUSR);
12721289
if (fd<0)
1273-
elog(STOP,"InitCreate(logfile %u seg %u) failed: %m",
1274-
log,seg);
1290+
elog(STOP,"InitCreate(%s) failed: %m",tmppath);
12751291

12761292
/*
12771293
* Zero-fill the file. We have to do this the hard way to ensure that
@@ -1290,36 +1306,73 @@ XLogFileInit(uint32 log, uint32 seg, bool *usexistent)
12901306
intsave_errno=errno;
12911307

12921308
/* If we fail to make the file, delete it to release disk space */
1293-
unlink(tpath);
1309+
unlink(tmppath);
12941310
errno=save_errno;
12951311

1296-
elog(STOP,"ZeroFill(logfile %u seg %u) failed: %m",
1297-
log,seg);
1312+
elog(STOP,"ZeroFill(%s) failed: %m",tmppath);
12981313
}
12991314
}
13001315

13011316
if (pg_fsync(fd)!=0)
1302-
elog(STOP,"fsync(logfile %u seg %u) failed: %m",
1303-
log,seg);
1317+
elog(STOP,"fsync(%s) failed: %m",tmppath);
13041318

13051319
close(fd);
13061320

13071321
/*
1308-
* Prefer link() to rename() here just to be sure that we don't overwrite
1309-
* an existing logfile. However, there shouldn't be one, so rename()
1310-
* is an acceptable substitute except for the truly paranoid.
1322+
* Now move the segment into place with its final name. We want to be
1323+
* sure that only one process does this at a time.
1324+
*/
1325+
if (use_lock)
1326+
SpinAcquire(ControlFileLockId);
1327+
1328+
/*
1329+
* If caller didn't want to use a pre-existing file, get rid of any
1330+
* pre-existing file. Otherwise, cope with possibility that someone
1331+
* else has created the file while we were filling ours: if so, use
1332+
* ours to pre-create a future log segment.
1333+
*/
1334+
targlog=log;
1335+
targseg=seg;
1336+
strcpy(targpath,path);
1337+
1338+
if (!*use_existent)
1339+
{
1340+
unlink(targpath);
1341+
}
1342+
else
1343+
{
1344+
while ((fd=BasicOpenFile(targpath,O_RDWR |PG_BINARY,
1345+
S_IRUSR |S_IWUSR)) >=0)
1346+
{
1347+
close(fd);
1348+
NextLogSeg(targlog,targseg);
1349+
XLogFileName(targpath,targlog,targseg);
1350+
}
1351+
}
1352+
1353+
/*
1354+
* Prefer link() to rename() here just to be really sure that we don't
1355+
* overwrite an existing logfile. However, there shouldn't be one, so
1356+
* rename() is an acceptable substitute except for the truly paranoid.
13111357
*/
13121358
#ifndef__BEOS__
1313-
if (link(tpath,path)<0)
1359+
if (link(tmppath,targpath)<0)
13141360
elog(STOP,"InitRelink(logfile %u seg %u) failed: %m",
1315-
log,seg);
1316-
unlink(tpath);
1361+
targlog,targseg);
1362+
unlink(tmppath);
13171363
#else
1318-
if (rename(tpath,path)<0)
1364+
if (rename(tmppath,targpath)<0)
13191365
elog(STOP,"InitRelink(logfile %u seg %u) failed: %m",
1320-
log,seg);
1366+
targlog,targseg);
13211367
#endif
13221368

1369+
if (use_lock)
1370+
SpinRelease(ControlFileLockId);
1371+
1372+
/* Set flag to tell caller there was no existent file */
1373+
*use_existent= false;
1374+
1375+
/* Now open original target segment (might not be file I just made) */
13231376
fd=BasicOpenFile(path,O_RDWR |PG_BINARY |XLOG_SYNC_BIT,
13241377
S_IRUSR |S_IWUSR);
13251378
if (fd<0)
@@ -1367,39 +1420,27 @@ PreallocXlogFiles(XLogRecPtr endptr)
13671420
uint32_logId;
13681421
uint32_logSeg;
13691422
intlf;
1370-
boolusexistent;
1371-
structtimevaldelay;
1423+
booluse_existent;
13721424
inti;
13731425

13741426
XLByteToPrevSeg(endptr,_logId,_logSeg);
13751427
if (XLOGfiles>0)
13761428
{
13771429
for (i=1;i <=XLOGfiles;i++)
13781430
{
1379-
usexistent= true;
13801431
NextLogSeg(_logId,_logSeg);
1381-
SpinAcquire(ControlFileLockId);
1382-
lf=XLogFileInit(_logId,_logSeg,&usexistent);
1432+
use_existent= true;
1433+
lf=XLogFileInit(_logId,_logSeg,&use_existent, true);
13831434
close(lf);
1384-
SpinRelease(ControlFileLockId);
1385-
/*
1386-
* Give up ControlFileLockId for 1/50 sec to let other
1387-
* backends switch to new log file in XLogWrite()
1388-
*/
1389-
delay.tv_sec=0;
1390-
delay.tv_usec=20000;
1391-
(void)select(0,NULL,NULL,NULL,&delay);
13921435
}
13931436
}
13941437
elseif ((endptr.xrecoff-1) %XLogSegSize >=
13951438
(uint32) (0.75*XLogSegSize))
13961439
{
1397-
usexistent= true;
13981440
NextLogSeg(_logId,_logSeg);
1399-
SpinAcquire(ControlFileLockId);
1400-
lf=XLogFileInit(_logId,_logSeg,&usexistent);
1441+
use_existent= true;
1442+
lf=XLogFileInit(_logId,_logSeg,&use_existent, true);
14011443
close(lf);
1402-
SpinRelease(ControlFileLockId);
14031444
}
14041445
}
14051446

@@ -2103,7 +2144,7 @@ BootStrapXLOG(void)
21032144
char*buffer;
21042145
XLogPageHeaderpage;
21052146
XLogRecord*record;
2106-
boolusexistent= false;
2147+
booluse_existent;
21072148
crc64crc;
21082149

21092150
/* Use malloc() to ensure buffer is MAXALIGNED */
@@ -2144,7 +2185,8 @@ BootStrapXLOG(void)
21442185
FIN_CRC64(crc);
21452186
record->xl_crc=crc;
21462187

2147-
openLogFile=XLogFileInit(0,0,&usexistent);
2188+
use_existent= false;
2189+
openLogFile=XLogFileInit(0,0,&use_existent, false);
21482190

21492191
if (write(openLogFile,buffer,BLCKSZ)!=BLCKSZ)
21502192
elog(STOP,"BootStrapXLOG failed to write logfile: %m");

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