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

On Wed, Dec 14, 2011 at 3:20 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Pavan Deolasee <pavan.deolasee@gmail.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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 Simon Riggs                   http://www.2ndQuadrant.com/
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