Re: Ragged latency log data in multi-threaded pgbench

Greg Smith <greg(at)2ndquadrant(dot)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