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From: Michael Fischer <mfischer@zendesk.com>
To: unicorn list <mongrel-unicorn@rubyforge.org>
Subject: Re: pid file handling issue
Date: Wed, 23 Oct 2013 18:01:33 -0700	[thread overview]
Message-ID: <CABHxtY5m4fNNXS7qMP8LEwbnJDA9nvnkMvzVD=VXcKVsY2RxyQ@mail.gmail.com> (raw)
In-Reply-To: <20131024005316.GA10239@dcvr.yhbt.net>

On Wed, Oct 23, 2013 at 5:53 PM, Eric Wong <normalperson@yhbt.net> wrote:

> I read and stash the value of the pid file before issuing any USR2.
> Later, you can issue "kill -0 $old_pid" after sending SIGQUIT
> to ensure it's dead.

That's inherently racy; another process can claim the old PID in the interim.

> Checking the mtime of the pidfile is really bizarre...

Perhaps (though it's a normative criticism), but on the other hand, it
isn't subject to the race above.

> OTOH, there's times when users accidentally remove a pid
> file and regenerate by hand it from ps(1), too...

Sure, but (a) that's a corner case I'm not particularly concerned
about, and (b) it wouldn't cause any problems, assuming the user did
this before any reload attempt, and not in the middle or something.

--Michael
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  reply	other threads:[~2013-10-24  1:01 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-23 22:55 pid file handling issue Michael Fischer
2013-10-24  0:53 ` Eric Wong
2013-10-24  1:01   ` Michael Fischer [this message]
2013-10-24  2:03     ` Eric Wong
2013-10-24 17:51       ` Michael Fischer
2013-10-24 18:21         ` Eric Wong
2013-10-24 19:57           ` Michael Fischer
2013-10-24 20:27             ` Eric Wong
2013-10-24 22:58             ` Eric Wong
2013-10-25  7:33               ` Hongli Lai
2013-10-25 20:31                 ` Eric Wong

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