New subject: [Bug 947444] PerlIO dead-locks with threaded fork

2 Apr 2013


      Product: Fedora
https://bugzilla.redhat.com/show_bug.cgi?id=947444
Bug ID: 947444
           Summary: PerlIO dead-locks with threaded fork
           Product: Fedora
           Version: 18
         Component: perl
          Severity: unspecified
          Priority: unspecified
          Assignee: mmaslano@redhat.com
          Reporter: ppisar@redhat.com
        QA Contact: extras-qa@fedoraproject.org
                CC: cweyl@alumni.drew.edu, iarnell@gmail.com,
                    jplesnik@redhat.com, kasal@ucw.cz, lkundrak@v3.sk,
                    mmaslano@redhat.com,
                    perl-devel@lists.fedoraproject.org, ppisar@redhat.com,
                    psabata@redhat.com, rc040203@freenet.de,
                    tcallawa@redhat.com
          Category: ---
Created attachment 730746
  --> https://bugzilla.redhat.com/attachment.cgi?id=730746&action=edit
Test case
As reported to upstream, there is a possible dead lock when using fork from
threads and PerlIO https://rt.perl.org/rt3/Public/Bug/Display.html?id=106212.
This has been fixed in commit:
...
From 4da80956418bbe1fdc23cad0b1cbb24cd7b87609 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrik=20H=C3=A4gglund?= patrik.h.hagglund@ericsson.com
Date: Sat, 2 Feb 2013 20:21:05 +0100
Subject: [PATCH] PATCH [perl #106212] Add PL_perlio_mutex to
 atfork_lock/unlock
Using threads + fork() on Linux, and IO operations in the threads, the
PL_perlio_mutex may be left in a locked state at the call of fork(),
potentially leading to deadlock in the child process at subsequent IO
operations. (Threads are pre-empted and not continued in the child
process after the fork.)
Therefore, ensure that the PL_perlio_mutex is unlocked in the child
process, right after fork(), by using atfork_lock/unlock.
(The RT text gives ways to reproduce the problem, but are not easily
added to Perl's test suite)
Probably all Fedoras are affected.
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[Bug 947444] New: PerlIO dead-locks with threaded fork