From: Ben Weintraub <benweint@...>
Date: 2013-01-18T10:11:53+09:00
Subject: Background threads and Process.daemon

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Hello all,

I'm seeing some unexpected behavior with background threads and
Process.daemon, and wondering whether I'm just doing something
wrong/unsupported, or if I've hit upon a Ruby bug.

Here's a test case that exposes the oddness I'm seeing:
https://gist.github.com/4561056

This code spawns a background thread that loops calling sleep(1)
repeatedly, then calls Process.daemon, and finally puts the main thread
into a sleep loop.

To reproduce the strangeness, run it, find the PID of the daemonized
process, and send it SIGQUIT. Instead of exiting, the process gets stuck in
a loop in rb_thread_terminate_all that looks like this:
https://gist.github.com/4561403

In addition, after daemonization, attaching to the process with gdb shows
only 2 native threads. Prior to daemonization, three native threads are
visible from gdb.

Is this (creating a background thread and then daemonizing) expected to
work? Am I doing something else wrong here?  I'm using ruby 1.9.3p327 on
Mac OS X 10.8.2.

Thanks!
Ben

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<div dir=3D"ltr">Hello all,<div><br></div><div>I&#39;m seeing some unexpect=
ed behavior with background threads and Process.daemon, and wondering wheth=
er I&#39;m just doing something wrong/unsupported, or if I&#39;ve hit upon =
a Ruby bug.</div>
<div><br></div><div>Here&#39;s a test case that exposes the oddness I&#39;m=
 seeing:</div><div><a href=3D"https://gist.github.com/4561056">https://gist=
.github.com/4561056</a><br></div><div><br></div><div style>This code spawns=
 a background thread that loops calling sleep(1) repeatedly, then calls Pro=
cess.daemon, and finally puts the main thread into a sleep loop.</div>
<div style><br></div><div style>To reproduce the strangeness, run it, find =
the PID of the daemonized process, and send it SIGQUIT. Instead of exiting,=
 the process gets stuck in a loop in rb_thread_terminate_all=A0that looks l=
ike this:</div>
<div style><a href=3D"https://gist.github.com/4561403">https://gist.github.=
com/4561403</a><br></div><div style><br></div><div style>In addition, after=
 daemonization, attaching to the process with gdb shows only 2 native threa=
ds. Prior to daemonization, three native threads are visible from gdb.</div=
>
<div style><br></div><div style>Is this (creating a background thread and t=
hen daemonizing) expected to work? Am I doing something else wrong here? =
=A0I&#39;m using ruby=A01.9.3p327 on Mac OS X 10.8.2.</div><div style><br><=
/div>
<div style>Thanks!</div><div style>Ben</div></div>

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