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Date: Tue, 21 Feb 2017 12:02:16 -0800
From: Jeremy Evans <code@jeremyevans.net>
To: Eric Wong <e@80x24.org>
Cc: unicorn-public@bogomips.org
Subject: Re: Patch: Add after_worker_exit configuration option
Message-ID: <20170221200216.GJ93742@jeremyevans.local>
References: <20170221191923.GH93742@jeremyevans.local>
 <20170221194320.GA26617@whir>
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On 02/21 07:43, Eric Wong wrote:
> Jeremy Evans <code@jeremyevans.net> wrote:
> > This option can be used to implement custom behavior for handling
> > worker exits.  For example, let's say you have a specific request
> > that crashes a worker process, which you expect to be due to a
> > improperly programmed C extension. By modifying your worker to
> > save request related data in a temporary file and using this option,
> > you can get a record of what request is crashing the application,
> > which will make debugging easier.
> > 
> > This is not a complete patch as it doesn't include tests, but
> > before writing tests I wanted to see if this is something you'd
> > consider including in unicorn.
> 
> What advantage does this have over Ruby's builtin at_exit?

at_exit is not called if the interpreter crashes:

ruby -e 'at_exit{File.write('a.txt', 'a')}; Process.kill :SEGV, $$' 2>/dev/null
([ -f a.txt ] && echo at_exit called) || echo at_exit not called

> 
> AFAIK, at_exit may be registered inside after_fork hooks to the
> same effect.
> 
> Thanks.