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Fix incorrect initialization of ProcGlobal->startupBufferPinWaitBufId. 

It was initialized in the wrong place and to the wrong value.  With bad
luck this could result in incorrect query-cancellation failures in hot
standby sessions, should a HS backend be holding pin on buffer number 1
while trying to acquire a lock.
This commit is contained in:
Tom Lane 2011-08-02 13:23:52 -04:00
parent 89df948ec2
commit 2e53bd5517
3 changed files with 7 additions and 8 deletions
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3
src/backend/storage/buffer/bufmgr.c
View File

@ -2449,10 +2449,11 @@ LockBufferForCleanup(Buffer buffer)
/* Wait to be signaled by UnpinBuffer() */
if (InHotStandby)
{
/* Share the bufid that Startup process waits on */
/* Publish the bufid that Startup process waits on */
SetStartupBufferPinWaitBufId(buffer - 1);
/* Set alarm and then wait to be signaled by UnpinBuffer() */
ResolveRecoveryConflictWithBufferPin();
/* Reset the published bufid */
SetStartupBufferPinWaitBufId(-1);
}
else

10
src/backend/storage/lmgr/proc.c
View File

@ -171,6 +171,9 @@ InitProcGlobal(void)
ProcGlobal->spins_per_delay = DEFAULT_SPINS_PER_DELAY;
ProcGlobal->freeProcs = NULL;
ProcGlobal->autovacFreeProcs = NULL;
ProcGlobal->startupProc = NULL;
ProcGlobal->startupProcPid = 0;
ProcGlobal->startupBufferPinWaitBufId = -1;
/*
* Create and initialize all the PGPROC structures we'll need (except for
@ -493,7 +496,6 @@ PublishStartupProcessInformation(void)
procglobal->startupProc = MyProc;
procglobal->startupProcPid = MyProcPid;
procglobal->startupBufferPinWaitBufId = 0;
SpinLockRelease(ProcStructLock);
}
@ -520,14 +522,10 @@ SetStartupBufferPinWaitBufId(int bufid)
int
GetStartupBufferPinWaitBufId(void)
{
int bufid;
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
bufid = procglobal->startupBufferPinWaitBufId;
return bufid;
return procglobal->startupBufferPinWaitBufId;
}
/*

2
src/include/storage/proc.h
View File

@ -178,7 +178,7 @@ typedef struct PROC_HDR
/* The proc of the Startup process, since not in ProcArray */
PGPROC *startupProc;
int startupProcPid;
/* Buffer id of the buffer that Startup process waits for pin on */
/* Buffer id of the buffer that Startup process waits for pin on, or -1 */
int startupBufferPinWaitBufId;
} PROC_HDR;