Re: LWLock Queue Jumping

Heikki Linnakangas wrote:
> Greg Stark wrote:
>> On Fri, Aug 28, 2009 at 8:07 PM, Simon Riggs wrote:
>>> WALInsertLock is heavily contended and likely always will be even if we
>>> apply some of the planned fixes.
>> I've lost any earlier messages, could you resend the raw data on which
>> this is based?
> 
> I don't have any pointers right now, but WALInsertLock does often show
> up as a bottleneck in write-intensive benchmarks.

yeah I recently ran accross that issue with testing concurrent COPY 
performance:

http://www.kaltenbrunner.cc/blog/index.php?/archives/27-Benchmarking-8.4-Chapter-2bulk-loading.html
discussed here:

http://archives.postgresql.org/pgsql-hackers/2009-06/msg01019.php


and (iirc) also here:

http://archives.postgresql.org/pgsql-hackers/2009-06/msg01133.php


however the general issue is easily visible in almost any write 
intensive concurrent workload on a fast IO subsystem(ie 
pgbench,sysbench,...).


Stefan