Re: Deterioration in performance when query executed in multi threads

Hi Ken,
Thanks for your answer. My test is actually running with jboss 7/jdbc and the connection pool is defined  with
min-pool-size=10 and max-pool-size=400. 

Why would you think it is an issue with the connection pool?

Thanks,
Anne


-----Original Message-----
From: ktm@rice.edu [mailto:ktm@rice.edu]
Sent: Wednesday, May 01, 2013 7:13 AM
To: Anne Rosset
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Deterioration in performance when query executed in multi threads

On Wed, May 01, 2013 at 02:05:06PM +0000, Anne Rosset wrote:
> Hi all,
> We are running a stress test that executes one select query with multiple threads.
> The query executes very fast (10ms). It returns 100 rows.  I see deterioration in the performance when we have
multiplethreads executing the query. With 100 threads, the query takes between 3s and 8s. 
>
> I suppose there is a way to tune our database. What are the parameters
> I should look into? (shared_buffer?, wal_buffer?)
>
> Thanks for your help,
> Anne

Try a connection pooler like pgbouncer to keep the number of simultaneous queries bounded to a reasonable number. You
willactually get better performance. 

Regards,
Ken