From: Jos Backus <jos@...>
Date: 2007-08-18T02:59:52+09:00
Subject: Slave not removing slave_proc_* files

Hi. In order to be able to run swiftiply_mongrel_rails under daemontools I
patched swiftiply_mongrel_rails to use Ara's Slave library. The patch does
essentially this:

    slaves = []  
    3.times do |i|
      require 'slave'
      require "#{File.dirname(__FILE__)}/mongrel_rails"
      slaves << Slave.object(:async => true) {
	Mongrel::Runner.new.run(args) # args == similar to mongrel_rails
	                              # command line args
      }
    end
    slaves.each {|t| t.join}

(See http://rubyforge.org/pipermail/swiftiply-users/2007-August/000054.html
for the actual patch).

Note that Mongrel::Runner.new.run never returns, hence the use of the :async
option. It is just a wrapper around mongrel_rails.

When a SIGTERM is sent to the swiftiply_mongrel_rails process, the following
output is seen:

    http://pastie.caboo.se/88665

This shows swiftiply_mongrel_rails as well as its slaves exiting, and
daemontools subsequently restarting swiftiply_mongrel_rails.

Now for the problem: after this, /tmp holds 3 slave_proc_* UNIX domain sockets
that have not been unlinked. Subsequent restarts yield more slave_proc_*
sockets, and so on.

So my question is: what could cause these sockets not to be removed? am I
using Slave incorrectly? I instrumented slave.rb to make sure the
Kernel.at_exit method is called and it is - it's just that the associated
block isn't executed in the SIGTERM case. It works fine when a SIGUSR2 signal
is sent - the sockets are cleaned up as expected. A simple test script
suggests that Kernel.at_exit works okay on the platform (ruby 1.8.5 from the
CentOS testing repo on CentOS 4).

Any help is appreciated...

-- 
Jos Backus
jos at catnook.com