From: Aliaksey Kandratsenka <redmine@...>
Date: 2010-04-05T20:14:54+09:00
Subject: [ruby-core:29263] [Bug #3100] Lockup in child after fork

Bug #3100: Lockup in child after fork
http://redmine.ruby-lang.org/issues/show/3100

Author: Aliaksey Kandratsenka
Status: Open, Priority: Normal
Category: core
ruby -v: ruby 1.8.7 (2010-01-10 patchlevel 249) [i486-linux]

I was using PTY.spawn and found a bug. I'm attaching a small testcase that at least on 2 my machines gives quite probable ruby process lockup in child.

I'm also attaching gdb backtrace of locked up child. It can be seen that we're stuck in NTPL's low-level lock that protects timer thread condition variable. So it looks like I'm doing fork at 'right' time, when this condition is being signaled in parent.

P.S. I'm categorizing it as core even though I can reproduce this only via PTY.spawn, 'cause pty.c looks very much innocent.


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