Re: pgbench - minor fix for meta command only scripts

On Mon, Sep 11, 2017 at 4:49 AM, Fabien COELHO <coelho@cri.ensmp.fr> wrote:
> Ok, the problem was a little bit more trivial than I thought.
>
> The issue is that under a low rate there may be no transaction in progress,
> however the wait procedure was relying on select's timeout. If nothing is
> active there is nothing to wait for, thus it was an active loop in this
> case...
>
> I've introduced a usleep call in place of select for this particular case.
> Hopefully this is portable.
>
> ISTM that this bug exists since rate was introduced, so shame on me and
> back-patching should be needed.

I took a look at this and found that the proposed patch applies
cleanly all the way back to 9.5, but the regression is reported to
have begun with a commit that starts in v10.  I haven't probed into
this in any depth, but are we sure that
12788ae49e1933f463bc59a6efe46c4a01701b76 is in fact where this problem
originated?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company