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Add some code to Assert that when we release pin on a buffer, we are 

not holding the buffer's cntx_lock or io_in_progress_lock.  A recent
report from Litao Wu makes me wonder whether it is ever possible for
us to drop a buffer and forget to release its cntx_lock.  The Assert
does not fire in the regression tests, but that proves little ...
This commit is contained in:
Tom Lane 2004-06-11 16:43:24 +00:00
parent 8d64b56206
commit e6cba71503
3 changed files with 29 additions and 3 deletions
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7
src/backend/storage/buffer/bufmgr.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.169 2004/05/31 20:31:33 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.170 2004/06/11 16:43:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -611,7 +611,12 @@ UnpinBuffer(BufferDesc *buf)
Assert(PrivateRefCount[b] > 0);
PrivateRefCount[b]--;
if (PrivateRefCount[b] == 0)
{
buf->refcount--;
/* I'd better not still hold any locks on the buffer */
Assert(!LWLockHeldByMe(buf->cntx_lock));
Assert(!LWLockHeldByMe(buf->io_in_progress_lock));
}
if ((buf->flags & BM_PIN_COUNT_WAITER) != 0 &&
buf->refcount == 1)

22
src/backend/storage/lmgr/lwlock.c
View File

@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.19 2003/12/20 17:31:21 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.20 2004/06/11 16:43:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -519,3 +519,23 @@ LWLockReleaseAll(void)
LWLockRelease(held_lwlocks[num_held_lwlocks - 1]);
}
}
/*
* LWLockHeldByMe - test whether my process currently holds a lock
*
* This is meant as debug support only. We do not distinguish whether the
* lock is held shared or exclusive.
*/
bool
LWLockHeldByMe(LWLockId lockid)
{
int i;
for (i = 0; i < num_held_lwlocks; i++)
{
if (held_lwlocks[i] == lockid)
return true;
}
return false;
}

3
src/include/storage/lwlock.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.11 2004/05/31 03:48:10 tgl Exp $
* $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.12 2004/06/11 16:43:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -62,6 +62,7 @@ extern void LWLockAcquire(LWLockId lockid, LWLockMode mode);
extern bool LWLockConditionalAcquire(LWLockId lockid, LWLockMode mode);
extern void LWLockRelease(LWLockId lockid);
extern void LWLockReleaseAll(void);
extern bool LWLockHeldByMe(LWLockId lockid);
extern int NumLWLocks(void);
extern int LWLockShmemSize(void);