Re: BUG #8326: pgbench tps wrong BUG - Mailing list pgsql-bugs

From Fabien COELHO
Subject Re: BUG #8326: pgbench tps wrong BUG
Date
Msg-id alpine.DEB.2.02.1307260857150.4397@localhost6.localdomain6
Whole thread Raw
In response to BUG #8326: pgbench tps wrong BUG  (digoal@126.com)
Responses Re: BUG #8326: pgbench tps wrong BUG  (digoal <digoal@126.com>)
List pgsql-bugs
> when client thread big, the tps without connection time wrong!!!!
> number of threads: 100
> duration: 10 s

My 0.02 €:

I cannot test that on my laptop! What kind of server is this?

The thread start time is currently taken before thread creation. The
overhead of creating 100 threads compared to 10 seconds of run is quite
significant and may impact the result. The second issue is that 800
connections and as many server processes must be created, and the time for
that must be quite significant as well against the 10 second run.

So I would mostly classify that as a feature rather than a bug, because
the run is so short.

BTW, I'm planning to submit an enhancement patch to pgbench to improve
measurements, that will include moving the start time after the thread is
started, and possibly help getting more consistent figures.

--
Fabien.

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