From: Tom Lane <tgl@sss.pgh.pa.us>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: pgsql-hackers@postgresql.org
Subject: Re: SSI atomic commit
Date: Tue, 05 Jul 2011 14:16:20 -0400
Message-ID: <21785.1309889780@sss.pgh.pa.us> (raw)
In-Reply-To: <4E13516F.50301@enterprisedb.com>
References: <4E12FDA8020000250003EFC1@gw.wicourts.gov>
<4E13516F.50301@enterprisedb.com>
Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> Hmm, I think it would be simpler to decide that instead of
> SerializableXactHashLock, you must hold ProcArrayLock to access
> LastSxactCommitSeqNo, and move the assignment of commitSeqNo to
> ProcArrayTransaction(). It's probably easiest to move
> LastSxactCommitSeqno to ShmemVariableCache too. There's a few places
> that would then need to acquire ProcArrayLock to read
> LastSxactCommitSeqno, but I feel it might still be much simpler that way.
Yeah ... this patch creats the need to hold both
SerializableXactHashLock and ProcArrayLock during transaction commit,
which is a bit scary from a deadlock-risk perspective, and not pleasant
from the concurrency standpoint either. It'd be better to push some
functionality into the procarray code.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, heikki.linnakangas@enterprisedb.com, Kevin.Grittner@wicourts.gov
Subject: Re: SSI atomic commit
In-Reply-To: <21785.1309889780@sss.pgh.pa.us>
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