From: Alvaro Herrera <alvherre@commandprompt.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Gregory Stark <stark@enterprisedb.com>
Cc: ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: pgsql-hackers@postgresql.org
Subject: Re: CSStorm occurred again by postgreSQL8.2
Date: Thu, 14 Sep 2006 10:22:22 -0400
Message-ID: <20060914142222.GA525@alvh.no-ip.org> (raw)
In-Reply-To: <28515.1158242279@sss.pgh.pa.us>
References: <20060808110913.50FA.ITAGAKI.TAKAHIRO@oss.ntt.co.jp>
<200608260346.k7Q3k2g06954@momjian.us>
<20060828181312.5638.ITAGAKI.TAKAHIRO@oss.ntt.co.jp>
<13251.1157299738@sss.pgh.pa.us>
<22080.1158198335@sss.pgh.pa.us>
<87mz92so6n.fsf@enterprisedb.com>
<27509.1158237711@sss.pgh.pa.us>
<28167.1158241250@sss.pgh.pa.us>
<28515.1158242279@sss.pgh.pa.us>
Tom Lane wrote:
> I wrote:
> > I see a bug though, which is that RecordSubTransactionAbort() calls
> > GetCurrentTransactionId() before having verified that it needs to do
> > anything. This means that we'll generate and then discard an XID
> > uselessly in a failed subxact that didn't touch disk.
>
> Well, it would be a bug except that RecordSubTransactionAbort isn't
> called unless the current subxact has an XID. Perhaps a comment would
> be appropriate but there's nothing to fix here.
>
> I think Theo's problem is probably somewhere else, too --- apparently
> it's not so much that TransactionIdIsCurrentTransactionId takes a long
> time as that something is calling it lots of times with no check for
> interrupt.
Could it be something like heap_lock_tuple? It calls MultiXactIdWait,
which calls GetMultXactIdMembers and TransactionIdIsCurrentTransactionId
on each member. (heap_update and heap_delete do the same thing). I
must admit I didn't read Theo's description on his scenario though.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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To: pgsql-hackers@postgresql.org
Cc: alvherre@commandprompt.com, tgl@sss.pgh.pa.us, stark@enterprisedb.com, itagaki.takahiro@oss.ntt.co.jp, bruce@momjian.us
Subject: Re: CSStorm occurred again by postgreSQL8.2
In-Reply-To: <20060914142222.GA525@alvh.no-ip.org>
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