From: Eric Wong <normalperson@yhbt.net>
To: mongrel-unicorn@rubyforge.org
Cc: Pai-Hung Chen <paihungchen@hotmail.com>
Subject: Re: How to automate the restarting of Unicorn?
Date: Mon, 10 Oct 2011 14:27:41 -0700 [thread overview]
Message-ID: <20111010212741.GA3828@dcvr.yhbt.net> (raw)
In-Reply-To: <loom.20111010T222728-376@post.gmane.org>
Pai-Hung Chen <paihungchen@hotmail.com> wrote:
> > On 10/10/2011 08:04 AM, Devin Ben-Hur wrote:
> > >> My question is: By the time the "before_exec" hook is executed, is it
> > >> guaranteed that unicorn.pid.oldbin ahas lready created (otherwise we
> > >> have a racing condition here)? Or is there a better way to achieve
> > >> what I want?
> > > I'm not 100% positive, but about 98% -- yes, you can count on the fact that
> the *.oldbin file will exist on
> > > disk before the before_exec block is executed. Eric can confirm this, but
> I've never had a problem with it...
> > No need to rely on authority, just read the source:
> > https://github.com/defunkt/unicorn/blob/master/lib/unicorn/http_server.rb
100% correct, source code never lies.
> Thanks for the pointer. The current source code clearly shows before_exec is
> called after the .oldbin file is created. I'd like to know if this is considered
> an "invariant" going forward.
Yes, there's no way to safely handle the pid file otherwise because of
race conditions you mentioned. The oldbin pid file must exist because
the new process (which calls before_exec) can clobber the regular pid
file once fork is called.
> Could someone in the "authority" help?
Fwiw, I'm only reluctantly an "authority". I'm against the notion of
authority. I am and forever will be nobody :)
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next prev parent reply other threads:[~2011-10-10 22:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-08 3:20 How to automate the restarting of Unicorn? Pai-Hung Chen
2011-10-09 23:31 ` Alex Sharp
2011-10-10 6:04 ` Devin Ben-Hur
2011-10-10 20:34 ` Pai-Hung Chen
2011-10-10 21:27 ` Eric Wong [this message]
2011-10-10 22:18 ` Pai-Hung Chen
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