Re: Ragged latency log data in multi-threaded pgbench - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Ragged latency log data in multi-threaded pgbench
Date
Msg-id 19142.1268669179@sss.pgh.pa.us
Whole thread Raw
In response to Ragged latency log data in multi-threaded pgbench  (Greg Smith <greg@2ndquadrant.com>)
List pgsql-hackers
Greg Smith <greg@2ndquadrant.com> writes:
> Looks like sometimes a client is only getting part of its line written 
> out before getting stomped on by the next one.  I think one of the 
> assumptions being made about how to safely write to this log file may be 
> broken by the multi-process implementation, which is what you get when 
> thread-safety is not available.

pgbench doesn't make any effort at all to avoid interleaved writes on
that file.  I don't think there is anything much that can be done about
it when you are using the forked-processes implementation.  It's
probably possible for it to show up on the multi-threads version too,
depending on how hard libc tries to interlock stdio calls.
        regards, tom lane


pgsql-hackers by date:

Previous
From: Andrew Dunstan
Date:
Subject: Re: Ragged latency log data in multi-threaded pgbench
Next
From: Merlin Moncure
Date:
Subject: Re: Dyamic updates of NEW with pl/pgsql