"Qingqing Zhou" <[EMAIL PROTECTED]> writes:
> "Tom Lane" <[EMAIL PROTECTED]> wrote
>> "Qingqing Zhou" <[EMAIL PROTECTED]> writes:
>>> After this, the proc->sem will be bumped to 1 unexpectedly ... Since
>>> this problem is rare, a possible fix is to put a critical section
>>> around line 1 to 7 and
"Tom Lane" <[EMAIL PROTECTED]> wrote
> "Qingqing Zhou" <[EMAIL PROTECTED]> writes:
> > After this, the proc->sem will be bumped to 1 unexpectedly ... Since
this
> > problem is rare, a possible fix is to put a critical section around line
1
> > to 7 and remove UnlockBuffers() accordingly.
>
> No, t
"Qingqing Zhou" <[EMAIL PROTECTED]> writes:
> ... However, a possible execution sequence involving another process
> doing UnpinBuffer() may look like this:
> unpinner: lockHdr(); read and reset flag; unlockHdr();
> waiter: lockHdr(); reset flag; unlockHdr(); ProcCancelWaitForSignal();
> unpinner
We have a wait-pin-to-1 mechanism in LockBufferForCleanup() like this:
1: bufHdr->wait_backend_pid = MyProcPid;
2: bufHdr->flags |= BM_PIN_COUNT_WAITER;
3: PinCountWaitBuf = bufHdr;
4: UnlockBufHdr_NoHoldoff(bufHdr);
5: LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
6: /* Wa
