Re: Race condition in HEAD, possibly due to PGPROC splitup

On Wed, Dec 14, 2011 at 3:20 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com> writes:
>> Looking at CommitTransaction(), it seems quite clear to me that we
>> call ProcArrayEndTransaction() before releasing the locks held by the
>> transaction. So its quite possible that when
>> GetRunningTransactionLocks goes through the list of currently held
>> locks, the pgxact->xid is already cleared. This seems to a old bug to
>> me and not related to PGXACT work.
>
> Hm.  So maybe the correct fix is to deem the lock already released
> if we get zero when we read the xid?  It's not clear to me what the
> requirements for GetRunningTransactionLocks actually are, but if it's
> okay for it to think a lock is released slightly ahead of when the
> rest of the system thinks so, that would work.

OK, I'll look at this.

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