From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Antonin Houska <antonin.houska@gmail.com>,
 "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: bgworker crashed or not?
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
 message dated "Mon, 03 Feb 2014 11:21:21 -0500"
Date: Mon, 03 Feb 2014 11:29:22 -0500
Message-ID: <32224.1391444962@sss.pgh.pa.us>
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Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Feb 3, 2014 at 10:20 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> So
>> exit(0) - done, permanently
>> exit(1) - done until restart interval
>> exit(other) - crash
>> and there's no way to obtain the "restart immediately" behavior?

> That's what I was thinking about, yes.  Of course, when the restart
> interval is 0, "done until restart interval" is the same as "restart
> immediately", so for anyone who wants to *always* restart immediately
> there is no problem.  Where you will run into trouble is if you
> sometimes want to wait for the restart interval and other times want
> to restart immediately.  But I'm not sure that's a real use case.  If
> it is, I suggest that we assign it some other, more obscure exit code
> and reserve 0 and 1 for what I believe will probably be the common
> cases.

Agreed, but after further reflection it seems like if you've declared
a restart interval, then "done until restart interval" is probably the
common case.  So how about

exit(0) - done until restart interval, or permanently if there is none
exit(1) - done permanently, even if a restart interval was declared
exit(other) - crash

I don't offhand see a point in an "exit and restart immediately" case.
Why exit at all, if you could just keep running?  If you *can't* just
keep running, it probably means you know you've bollixed something,
so that the crash case is probably what to do anyway.

> It would be potentially more useful and more general to have a
> function BackgroundWorkerSetMyRestartInterval() or similar.

That might be a good idea too, but I think it's orthogonal to what
the exit codes mean.

			regards, tom lane


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