Re: pgbench - minor fix for meta command only scripts

From: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
To: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: pgbench - minor fix for meta command only scripts
Date: 2016-09-26 08:01:01
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On 09/24/2016 12:45 PM, Fabien COELHO wrote:
> Although I cannot be absolutely sure that the refactoring does not
> introduce any new bug, I'm convinced that it will be much easier to find
> them:-)


> Attached are some small changes to your version:
> I have added the sleep_until fix.
> I have fixed a bug introduced in the patch by changing && by || in the
> (min_sec > 0 && maxsock != -1) condition which was inducing errors with
> multi-threads & clients...
> I have factored out several error messages in "commandFailed", in place of
> the "metaCommandFailed", and added the script number as well in the error
> messages. All messages are now specific to the failed command.
> I have added two states to the machine:
> - CSTATE_CHOOSE_SCRIPT which simplifies threadRun, there is now one call
> to chooseScript instead of two before.
> - CSTATE_END_COMMAND which manages is_latencies and proceeding to the
> next command, thus merging the three instances of updating the stats
> that were in the first version.
> The later state means that processing query results is included in the per
> statement latency, which is an improvement because before I was getting
> some transaction latency significantly larger that the apparent sum of the
> per-statement latencies, which did not make much sense...

Ok. I agree that makes more sense.

> I have added & updated a few comments.

Thanks! Committed.

> There are some places where the break could be a pass through
> instead, not sure how desirable it is, I'm fine with break.

I left them as "break". Pass-throughs are error-prone, and make it more
difficult to read, IMHO. The compiler will optimize it into a
pass-through anyway, if possible and worthwhile, so there should be no
performance difference.

- Heikki

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