Re: CheckpointStartLock starvation - Mailing list pgsql-hackers

From ITAGAKI Takahiro
Subject Re: CheckpointStartLock starvation
Date
Msg-id 20070403094025.C156.ITAGAKI.TAKAHIRO@oss.ntt.co.jp
Whole thread Raw
In response to CheckpointStartLock starvation  (Heikki Linnakangas <heikki@enterprisedb.com>)
Responses Re: CheckpointStartLock starvation  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Heikki Linnakangas <heikki@enterprisedb.com> wrote:

> It looks like the bgwriter gets starved waiting on the 
> CheckpointStartLock. The CheckpointStartLock is held in shared mode over 
> an XLogFlush when committing, which on an extremely busy system like a 
> benchmark is always long enough to have a new transaction to acquire the 
> CheckpointStartLock again.

If the starvation comes from giving unfair priorities on shared locks
against exclusive locks, does the below TODO item help us?

| Locking
| Fix priority ordering of read and write light-weight locks (Neil) 
| http://archives.postgresql.org/pgsql-hackers/2004-11/msg00893.php
| http://archives.postgresql.org/pgsql-hackers/2004-11/msg00905.php 

Regards,
---
ITAGAKI Takahiro
NTT Open Source Software Center




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