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Commit8a6fab4

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Remove ShutdownBufferPoolAccess exit callback, and do the work in
ProcKill instead, where we still have a PGPROC with which to wait onLWLocks. This fixes 'can't wait without a PROC structure' failuresoccasionally seen during backend shutdown (I'm surprised they weren'tmore frequent, actually). Add an Assert() to LWLockAcquire to helpcatch any similar mistakes in future. Fix failure to update MyProcPidfor standalone backends and pgstat processes.
1 parent691aefc commit8a6fab4

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6 files changed

+43
-34
lines changed

6 files changed

+43
-34
lines changed

‎src/backend/bootstrap/bootstrap.c

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.142 2002/09/22 19:42:50 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.143 2002/09/25 20:31:40 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -369,6 +369,9 @@ BootstrapMain(int argc, char *argv[])
369369

370370
BaseInit();
371371

372+
if (IsUnderPostmaster)
373+
InitDummyProcess();/* needed to get LWLocks */
374+
372375
/*
373376
* XLOG operations
374377
*/
@@ -386,8 +389,6 @@ BootstrapMain(int argc, char *argv[])
386389
break;
387390

388391
caseBS_XLOG_CHECKPOINT:
389-
if (IsUnderPostmaster)
390-
InitDummyProcess();/* needed to get LWLocks */
391392
CreateDummyCaches();
392393
CreateCheckPoint(false);
393394
SetSavedRedoRecPtr();/* pass redo ptr back to

‎src/backend/postmaster/pgstat.c

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,7 @@
1616
*
1717
*Copyright (c) 2001, PostgreSQL Global Development Group
1818
*
19-
*$Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.28 2002/09/05 18:26:18 petere Exp $
19+
*$Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.29 2002/09/25 20:31:40 tgl Exp $
2020
* ----------
2121
*/
2222
#include"postgres.h"
@@ -314,6 +314,8 @@ pgstat_start(void)
314314

315315
IsUnderPostmaster= true;/* we are a postmaster subprocess now */
316316

317+
MyProcPid=getpid();/* reset MyProcPid */
318+
317319
/* Lose the postmaster's on-exit routines */
318320
on_exit_reset();
319321

@@ -1190,6 +1192,8 @@ pgstat_main(void)
11901192
*/
11911193
pqsignal(SIGCHLD,SIG_DFL);
11921194

1195+
MyProcPid=getpid();/* reset MyProcPid */
1196+
11931197
/*
11941198
* Identify myself via ps
11951199
*/

‎src/backend/storage/buffer/buf_init.c

Lines changed: 5 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/buf_init.c,v 1.52 2002/09/04 20:31:25 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/storage/buffer/buf_init.c,v 1.53 2002/09/25 20:31:40 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -35,8 +35,6 @@
3535
#include"utils/memutils.h"
3636

3737

38-
staticvoidShutdownBufferPoolAccess(void);
39-
4038
/*
4139
*if BMTRACE is defined, we trace the last 200 buffer allocations and
4240
*deallocations in a circular buffer in shared memory.
@@ -219,6 +217,10 @@ InitBufferPool(void)
219217
* This is called during backend startup (whether standalone or under the
220218
* postmaster). It sets up for this backend's access to the already-existing
221219
* buffer pool.
220+
*
221+
* NB: this is called before InitProcess(), so we do not have a PGPROC and
222+
* cannot do LWLockAcquire; hence we can't actually access the bufmgr's
223+
* shared memory yet. We are only initializing local data here.
222224
*/
223225
void
224226
InitBufferPoolAccess(void)
@@ -238,27 +240,6 @@ InitBufferPoolAccess(void)
238240
*/
239241
for (i=0;i<NBuffers;i++)
240242
BufferBlockPointers[i]= (Block)MAKE_PTR(BufferDescriptors[i].data);
241-
242-
/*
243-
* Now that buffer access is initialized, set up a callback to shut it
244-
* down again at backend exit.
245-
*/
246-
on_shmem_exit(ShutdownBufferPoolAccess,0);
247-
}
248-
249-
/*
250-
* Shut down buffer manager at backend exit.
251-
*
252-
* This is needed mainly to ensure that we don't leave any buffer reference
253-
* counts set during an error exit.
254-
*/
255-
staticvoid
256-
ShutdownBufferPoolAccess(void)
257-
{
258-
/* Release any buffer context locks we are holding */
259-
UnlockBuffers();
260-
/* Release any buffer reference counts we are holding */
261-
AtEOXact_Buffers(false);
262243
}
263244

264245
/* -----------------------------------------------------

‎src/backend/storage/lmgr/lwlock.c

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,7 @@
1515
* Portions Copyright (c) 1994, Regents of the University of California
1616
*
1717
* IDENTIFICATION
18-
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lwlock.c,v 1.13 2002/09/04 20:31:26 momjian Exp $
18+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lwlock.c,v 1.14 2002/09/25 20:31:40 tgl Exp $
1919
*
2020
*-------------------------------------------------------------------------
2121
*/
@@ -203,6 +203,13 @@ LWLockAcquire(LWLockId lockid, LWLockMode mode)
203203

204204
PRINT_LWDEBUG("LWLockAcquire",lockid,lock);
205205

206+
/*
207+
* We can't wait if we haven't got a PGPROC. This should only occur
208+
* during bootstrap or shared memory initialization. Put an Assert
209+
* here to catch unsafe coding practices.
210+
*/
211+
Assert(!(proc==NULL&&IsUnderPostmaster));
212+
206213
/*
207214
* Lock out cancel/die interrupts until we exit the code section
208215
* protected by the LWLock. This ensures that interrupts will not

‎src/backend/storage/lmgr/proc.c

Lines changed: 12 additions & 3 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 1.125 2002/09/04 20:31:26 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.126 2002/09/25 20:31:40 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -391,8 +391,15 @@ ProcKill(void)
391391
/* Release any LW locks I am holding */
392392
LWLockReleaseAll();
393393

394-
/* Abort any buffer I/O in progress */
394+
/*
395+
* Make real sure we release any buffer locks and pins we might be
396+
* holding, too. It is pretty ugly to do this here and not in a
397+
* shutdown callback registered by the bufmgr ... but we must do this
398+
* *after* LWLockReleaseAll and *before* zapping MyProc.
399+
*/
395400
AbortBufferIO();
401+
UnlockBuffers();
402+
AtEOXact_Buffers(false);
396403

397404
/* Get off any wait queue I might be on */
398405
LockWaitCancel();
@@ -430,8 +437,10 @@ DummyProcKill(void)
430437
/* Release any LW locks I am holding */
431438
LWLockReleaseAll();
432439

433-
/*Abort anybufferI/O in progress */
440+
/*Releasebufferlocks and pins, too */
434441
AbortBufferIO();
442+
UnlockBuffers();
443+
AtEOXact_Buffers(false);
435444

436445
/* I can't be on regular lock queues, so needn't check */
437446

‎src/backend/tcop/postgres.c

Lines changed: 9 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/tcop/postgres.c,v 1.293 2002/09/20 03:45:08 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.294 2002/09/25 20:31:40 tgl Exp $
1212
*
1313
* NOTES
1414
* this is the "main" module of the postgres backend and
@@ -1163,6 +1163,13 @@ PostgresMain(int argc, char *argv[], const char *username)
11631163
}
11641164
}
11651165

1166+
/*
1167+
* initialize globals (already done if under postmaster, but not if
1168+
* standalone; cheap enough to do over)
1169+
*/
1170+
1171+
MyProcPid=getpid();
1172+
11661173
/*
11671174
* Fire up essential subsystems: error and memory management
11681175
*
@@ -1691,7 +1698,7 @@ PostgresMain(int argc, char *argv[], const char *username)
16911698
if (!IsUnderPostmaster)
16921699
{
16931700
puts("\nPOSTGRES backend interactive interface ");
1694-
puts("$Revision: 1.293 $ $Date: 2002/09/20 03:45:08 $\n");
1701+
puts("$Revision: 1.294 $ $Date: 2002/09/25 20:31:40 $\n");
16951702
}
16961703

16971704
/*

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