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Re: Ragged latency log data in multi-threaded pgbench

Takahiro Itagaki <itagaki.takahiro@oss.ntt.co.jp>

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From: Takahiro Itagaki <itagaki.takahiro@oss.ntt.co.jp>
To: Greg Smith <greg@2ndquadrant.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2010-03-16T00:46:47Z
Lists: pgsql-hackers 
Greg Smith <greg@2ndquadrant.com> wrote:

> It looks like the switch between clients running on separate workers can 
> lead to a mix of their respective lines showing up though.

Oops. There might be two solutions for the issue:
  1. Use explicit locks. The lock primitive will be pthread_mutex for
     multi-threaded implementations or semaphore for multi-threaded ones.
  2. Use per-thread log files.
     File names would be "pgbench_log.<main-process-id>.<thread-id>".

Which is better, or another idea?

Regards,
---
Takahiro Itagaki
NTT Open Source Software Center