To: drkp@csail.mit.edu
Cc: pgsql-hackers@postgresql.org, Kevin.Grittner@wicourts.gov,
	heikki.linnakangas@enterprisedb.com
Subject: Re: SSI bug?
In-Reply-To: Your message of "Sun, 3 Apr 2011 02:16:44 -0400"
	<20110403061644.GS81592@csail.mit.edu>
References: <20110403061644.GS81592@csail.mit.edu>
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Message-Id: <20110407020210.D851019CF0A@mail.netbsd.org>
Date: Thu,  7 Apr 2011 02:02:10 +0000 (UTC)
From: yamt@mwd.biglobe.ne.jp (YAMAMOTO Takashi)

hi,

> I think I see what is going on now. We are sometimes failing to set the
> commitSeqNo correctly on the lock. In particular, if a lock assigned to
> OldCommittedSxact is marked with InvalidSerCommitNo, it will never be
> cleared.
> 
> The attached patch corrects this:
>  TransferPredicateLocksToNewTarget should initialize a new lock
>  entry's commitSeqNo to that of the old one being transferred, or take
>  the minimum commitSeqNo if it is merging two lock entries.
> 
>  Also, CreatePredicateLock should initialize commitSeqNo for to
>  InvalidSerCommitSeqNo instead of to 0. (I don't think using 0 would
>  actually affect anything, but we should be consistent.)
> 
>  I also added a couple of assertions I used to track this down: a
>  lock's commitSeqNo should never be zero, and it should be
>  InvalidSerCommitSeqNo if and only if the lock is not held by
>  OldCommittedSxact.
> 
> Takashi, does this patch fix your problem with leaked SIReadLocks?

i'm currently running bf6848bc8c82e82f857d48185554bc3e6dcf1013 with this
patch applied.  i haven't seen the symptom yet.  i'll keep it running for
a while.

btw, i've noticed the following message in the server log.  is it normal?

LOG:  could not truncate directory "pg_serial": apparent wraparound

YAMAMOTO Takashi

> 
> Dan
> 
> 
> -- 
> Dan R. K. Ports              MIT CSAIL                http://drkp.net/