Re: Ragged latency log data in multi-threaded pgbench

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От Tom Lane
Тема Re: Ragged latency log data in multi-threaded pgbench
Дата
Msg-id 19142.1268669179@sss.pgh.pa.us
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Ответ на Ragged latency log data in multi-threaded pgbench  (Greg Smith <greg@2ndquadrant.com>)
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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


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