Re: Ragged latency log data in multi-threaded pgbench

Takahiro Itagaki <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> writes:
> Greg Smith <greg(at)2ndquadrant(dot)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>".

I think #1 is out of the question, as the synchronization overhead will
do serious damage to the whole point of having a multithreaded pgbench.
#2 might be a reasonable idea.

regards, tom lane