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Re: CheckpointStartLock starvation

From: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: CheckpointStartLock starvation
Date: 2007-04-03 13:51:52
Message-ID: 46125BF8.1040303@enterprisedb.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane wrote:
> Heikki Linnakangas <heikki(at)enterprisedb(dot)com> writes:
>> Tom Lane wrote:
>>> Nor will that work for prepared xacts --- you don't want to wait for the
>>> eventual commit, only for PREPARE TRANSACTION to exit its critical
>>> section.
> 
>> PREPARE TRANSACTION wouldn't set the flag in MyProc; there's no clog 
>> changes to protect from at that point. It would be set in 
>> RecordTransactionCommitPrepared when we're really committing. Just like 
>> we use the CheckpointStartLock today.
> 
> Indeed --- you'd better take another look at where we use the
> CheckpointStartLock today.

Yeah, while writing the patch I noticed that we really do use it in 
EndPrepare to avoid a similar race condition with the twophase state file..

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

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Subject: Re: Logging checkpoints and other slowdown causes
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