Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit227a404

Browse files
committed
Add code to print information about a detected deadlock cycle. The
printed data is comparable to what you could read in the pg_locks view,were you fortunate enough to have been looking at it at the right time.
1 parent136828c commit227a404

File tree

4 files changed

+166
-12
lines changed

4 files changed

+166
-12
lines changed

‎src/backend/storage/lmgr/deadlock.c‎

Lines changed: 149 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -12,11 +12,13 @@
1212
*
1313
*
1414
* IDENTIFICATION
15-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/deadlock.c,v 1.15 2002/11/01 00:40:23 tgl Exp $
15+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/deadlock.c,v 1.16 2003/01/16 21:01:44 tgl Exp $
1616
*
1717
*Interface:
1818
*
1919
*DeadLockCheck()
20+
*DeadLockReport()
21+
*RememberSimpleDeadLock()
2022
*InitDeadLockChecking()
2123
*
2224
*-------------------------------------------------------------------------
@@ -45,12 +47,27 @@ typedef struct
4547
intnProcs;
4648
}WAIT_ORDER;
4749

50+
/*
51+
* Information saved about each edge in a detected deadlock cycle. This
52+
* is used to print a diagnostic message upon failure.
53+
*
54+
* Note: because we want to examine this info after releasing the LockMgrLock,
55+
* we can't just store LOCK and PGPROC pointers; we must extract out all the
56+
* info we want to be able to print.
57+
*/
58+
typedefstruct
59+
{
60+
LOCKTAGlocktag;/* ID of awaited lock object */
61+
LOCKMODElockmode;/* type of lock we're waiting for */
62+
intpid;/* PID of blocked backend */
63+
}DEADLOCK_INFO;
64+
4865

4966
staticboolDeadLockCheckRecurse(PGPROC*proc);
5067
staticboolTestConfiguration(PGPROC*startProc);
5168
staticboolFindLockCycle(PGPROC*checkProc,
5269
EDGE*softEdges,int*nSoftEdges);
53-
staticboolFindLockCycleRecurse(PGPROC*checkProc,
70+
staticboolFindLockCycleRecurse(PGPROC*checkProc,intdepth,
5471
EDGE*softEdges,int*nSoftEdges);
5572
staticboolExpandConstraints(EDGE*constraints,intnConstraints);
5673
staticboolTopoSort(LOCK*lock,EDGE*constraints,intnConstraints,
@@ -88,6 +105,8 @@ static intmaxCurConstraints;
88105
staticEDGE*possibleConstraints;
89106
staticintnPossibleConstraints;
90107
staticintmaxPossibleConstraints;
108+
staticDEADLOCK_INFO*deadlockDetails;
109+
staticintnDeadlockDetails;
91110

92111

93112
/*
@@ -110,8 +129,10 @@ InitDeadLockChecking(void)
110129

111130
/*
112131
* FindLockCycle needs at most MaxBackends entries in visitedProcs[]
132+
* and deadlockDetails[].
113133
*/
114134
visitedProcs= (PGPROC**)palloc(MaxBackends*sizeof(PGPROC*));
135+
deadlockDetails= (DEADLOCK_INFO*)palloc(MaxBackends*sizeof(DEADLOCK_INFO));
115136

116137
/*
117138
* TopoSort needs to consider at most MaxBackends wait-queue entries,
@@ -176,6 +197,10 @@ InitDeadLockChecking(void)
176197
* table to have a different masterLock, all locks that can block had
177198
* better use the same LWLock, else this code will not be adequately
178199
* interlocked!
200+
*
201+
* On failure, deadlock details are recorded in deadlockDetails[] for
202+
* subsequent printing by DeadLockReport(). That activity is separate
203+
* because we don't want to do it while holding the master lock.
179204
*/
180205
bool
181206
DeadLockCheck(PGPROC*proc)
@@ -190,7 +215,19 @@ DeadLockCheck(PGPROC *proc)
190215

191216
/* Search for deadlocks and possible fixes */
192217
if (DeadLockCheckRecurse(proc))
218+
{
219+
/*
220+
* Call FindLockCycle one more time, to record the correct
221+
* deadlockDetails[] for the basic state with no rearrangements.
222+
*/
223+
intnSoftEdges;
224+
225+
nWaitOrders=0;
226+
if (!FindLockCycle(proc,possibleConstraints,&nSoftEdges))
227+
elog(FATAL,"DeadLockCheck: deadlock seems to have disappeared");
228+
193229
return true;/* cannot find a non-deadlocked state */
230+
}
194231

195232
/* Apply any needed rearrangements of wait queues */
196233
for (i=0;i<nWaitOrders;i++)
@@ -357,9 +394,12 @@ TestConfiguration(PGPROC *startProc)
357394
*
358395
* Scan outward from the given proc to see if there is a cycle in the
359396
* waits-for graph that includes this proc. Return TRUE if a cycle
360-
* is found, else FALSE. If a cycle is found, wealsoreturn a list of
397+
* is found, else FALSE. If a cycle is found, we return a list of
361398
* the "soft edges", if any, included in the cycle. These edges could
362-
* potentially be eliminated by rearranging wait queues.
399+
* potentially be eliminated by rearranging wait queues. We also fill
400+
* deadlockDetails[] with information about the detected cycle; this info
401+
* is not used by the deadlock algorithm itself, only to print a useful
402+
* message after failing.
363403
*
364404
* Since we need to be able to check hypothetical configurations that would
365405
* exist after wait queue rearrangement, the routine pays attention to the
@@ -372,12 +412,14 @@ FindLockCycle(PGPROC *checkProc,
372412
int*nSoftEdges)/* output argument */
373413
{
374414
nVisitedProcs=0;
415+
nDeadlockDetails=0;
375416
*nSoftEdges=0;
376-
returnFindLockCycleRecurse(checkProc,softEdges,nSoftEdges);
417+
returnFindLockCycleRecurse(checkProc,0,softEdges,nSoftEdges);
377418
}
378419

379420
staticbool
380421
FindLockCycleRecurse(PGPROC*checkProc,
422+
intdepth,
381423
EDGE*softEdges,/* output argument */
382424
int*nSoftEdges)/* output argument */
383425
{
@@ -402,7 +444,16 @@ FindLockCycleRecurse(PGPROC *checkProc,
402444
{
403445
/* If we return to starting point, we have a deadlock cycle */
404446
if (i==0)
447+
{
448+
/*
449+
* record total length of cycle --- outer levels will now
450+
* fill deadlockDetails[]
451+
*/
452+
Assert(depth <=MaxBackends);
453+
nDeadlockDetails=depth;
454+
405455
return true;
456+
}
406457

407458
/*
408459
* Otherwise, we have a cycle but it does not include the
@@ -449,8 +500,18 @@ FindLockCycleRecurse(PGPROC *checkProc,
449500
((1 <<lm)&conflictMask)!=0)
450501
{
451502
/* This proc hard-blocks checkProc */
452-
if (FindLockCycleRecurse(proc,softEdges,nSoftEdges))
503+
if (FindLockCycleRecurse(proc,depth+1,
504+
softEdges,nSoftEdges))
505+
{
506+
/* fill deadlockDetails[] */
507+
DEADLOCK_INFO*info=&deadlockDetails[depth];
508+
509+
info->locktag=lock->tag;
510+
info->lockmode=checkProc->waitLockMode;
511+
info->pid=checkProc->pid;
512+
453513
return true;
514+
}
454515
/* If no deadlock, we're done looking at this holder */
455516
break;
456517
}
@@ -496,8 +557,16 @@ FindLockCycleRecurse(PGPROC *checkProc,
496557
if (((1 <<proc->waitLockMode)&conflictMask)!=0)
497558
{
498559
/* This proc soft-blocks checkProc */
499-
if (FindLockCycleRecurse(proc,softEdges,nSoftEdges))
560+
if (FindLockCycleRecurse(proc,depth+1,
561+
softEdges,nSoftEdges))
500562
{
563+
/* fill deadlockDetails[] */
564+
DEADLOCK_INFO*info=&deadlockDetails[depth];
565+
566+
info->locktag=lock->tag;
567+
info->lockmode=checkProc->waitLockMode;
568+
info->pid=checkProc->pid;
569+
501570
/*
502571
* Add this edge to the list of soft edges in the
503572
* cycle
@@ -529,8 +598,16 @@ FindLockCycleRecurse(PGPROC *checkProc,
529598
if (((1 <<proc->waitLockMode)&conflictMask)!=0)
530599
{
531600
/* This proc soft-blocks checkProc */
532-
if (FindLockCycleRecurse(proc,softEdges,nSoftEdges))
601+
if (FindLockCycleRecurse(proc,depth+1,
602+
softEdges,nSoftEdges))
533603
{
604+
/* fill deadlockDetails[] */
605+
DEADLOCK_INFO*info=&deadlockDetails[depth];
606+
607+
info->locktag=lock->tag;
608+
info->lockmode=checkProc->waitLockMode;
609+
info->pid=checkProc->pid;
610+
534611
/*
535612
* Add this edge to the list of soft edges in the
536613
* cycle
@@ -758,3 +835,67 @@ PrintLockQueue(LOCK *lock, const char *info)
758835
}
759836

760837
#endif
838+
839+
/*
840+
* Report details about a detected deadlock.
841+
*/
842+
void
843+
DeadLockReport(void)
844+
{
845+
inti;
846+
847+
for (i=0;i<nDeadlockDetails;i++)
848+
{
849+
DEADLOCK_INFO*info=&deadlockDetails[i];
850+
intnextpid;
851+
852+
/* The last proc waits for the first one... */
853+
if (i<nDeadlockDetails-1)
854+
nextpid=info[1].pid;
855+
else
856+
nextpid=deadlockDetails[0].pid;
857+
858+
if (info->locktag.relId==XactLockTableId&&info->locktag.dbId==0)
859+
{
860+
/* Lock is for transaction ID */
861+
elog(NOTICE,"Proc %d waits for %s on transaction %u; blocked by %d",
862+
info->pid,
863+
GetLockmodeName(info->lockmode),
864+
info->locktag.objId.xid,
865+
nextpid);
866+
}
867+
else
868+
{
869+
/* Lock is for a relation */
870+
elog(NOTICE,"Proc %d waits for %s on relation %u database %u; blocked by %d",
871+
info->pid,
872+
GetLockmodeName(info->lockmode),
873+
info->locktag.relId,
874+
info->locktag.dbId,
875+
nextpid);
876+
}
877+
}
878+
}
879+
880+
/*
881+
* RememberSimpleDeadLock: set up info for DeadLockReport when ProcSleep
882+
* detects a trivial (two-way) deadlock. proc1 wants to block for lockmode
883+
* on lock, but proc2 is already waiting and would be blocked by proc1.
884+
*/
885+
void
886+
RememberSimpleDeadLock(PGPROC*proc1,
887+
LOCKMODElockmode,
888+
LOCK*lock,
889+
PGPROC*proc2)
890+
{
891+
DEADLOCK_INFO*info=&deadlockDetails[0];
892+
893+
info->locktag=lock->tag;
894+
info->lockmode=lockmode;
895+
info->pid=proc1->pid;
896+
info++;
897+
info->locktag=proc2->waitLock->tag;
898+
info->lockmode=proc2->waitLockMode;
899+
info->pid=proc2->pid;
900+
nDeadlockDetails=2;
901+
}

‎src/backend/storage/lmgr/lock.c‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.118 2002/11/01 00:40:23 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.119 2003/01/16 21:01:44 tgl Exp $
1212
*
1313
* NOTES
1414
* Outside modules can create a lock table and acquire/release
@@ -905,6 +905,13 @@ WaitOnLock(LOCKMETHOD lockmethod, LOCKMODE lockmode,
905905
*/
906906
LOCK_PRINT("WaitOnLock: aborting on lock",lock,lockmode);
907907
LWLockRelease(lockMethodTable->masterLock);
908+
/*
909+
* Now that we aren't holding the LockMgrLock, print details about
910+
* the detected deadlock. We didn't want to do this before because
911+
* sending elog messages to the client while holding the shared lock
912+
* is bad for concurrency.
913+
*/
914+
DeadLockReport();
908915
elog(ERROR,"deadlock detected");
909916
/* not reached */
910917
}

‎src/backend/storage/lmgr/proc.c‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.127 2002/10/31 21:34:16 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.128 2003/01/16 21:01:44 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -566,8 +566,9 @@ ProcSleep(LOCKMETHODTABLE *lockMethodTable,
566566
* up correctly is to call RemoveFromWaitQueue(), but
567567
* we can't do that until we are *on* the wait queue.
568568
* So, set a flag to check below, and break out of
569-
* loop.
569+
* loop. Also, record deadlock info for later message.
570570
*/
571+
RememberSimpleDeadLock(MyProc,lockmode,lock,proc);
571572
early_deadlock= true;
572573
break;
573574
}

‎src/include/storage/lock.h‎

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $Id: lock.h,v 1.67 2002/09/04 20:31:45momjian Exp $
10+
* $Id: lock.h,v 1.68 2003/01/16 21:01:45tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -243,6 +243,11 @@ extern void GrantLock(LOCK *lock, PROCLOCK *holder, LOCKMODE lockmode);
243243
externvoidRemoveFromWaitQueue(PGPROC*proc);
244244
externintLockShmemSize(intmaxBackends);
245245
externboolDeadLockCheck(PGPROC*proc);
246+
externvoidDeadLockReport(void);
247+
externvoidRememberSimpleDeadLock(PGPROC*proc1,
248+
LOCKMODElockmode,
249+
LOCK*lock,
250+
PGPROC*proc2);
246251
externvoidInitDeadLockChecking(void);
247252
externLockData*GetLockStatusData(void);
248253
externconstchar*GetLockmodeName(LOCKMODEmode);

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp