RE: [Boost-Users] bug in pthreads implementation of recursive_mut ex

From: Feldman, Yulik (yulik.feldman_at_[hidden])
Date: 2003-05-06 11:22:03

Thanks Alexander for the pointer to this long and interesting
discussion. I'll check my design whether I could get rid of the
recursive mutexes in order to reduce the probability of not holding
invariants when the wait() is called, especially since the code still
doesn't behave correctly, even after the Boost bug is fixed :)

William, unfortunately I don't have a small testcase for the bug and it
seems that it will be too time-consuming for me to try to prepare a
small "working" testcase. Thanks for confirming the bug report (it makes
me feel better that the debugging time was not wasted).

--Yulik.

-----Original Message-----
From: William E. Kempf [mailto:wekempf_at_[hidden]] 
Sent: Monday, May 05, 2003 6:44 PM
To: Boost-Users_at_[hidden]
Subject: Re: [Boost-Users] bug in pthreads implementation of
recursive_mutex

Feldman, Yulik said:
> Hi,
>
>
>
> It looks that there is a bug in
> .../boost_1_30_0/libs/thread/src/recursive_mutex.cpp. The bug shows in
> the pthreads implementation of the recursive_mutex when the mutex is
> used with the "condition" synchronization primitive. Here is the
> description of the bug:

You're evaluation of the bug is correct.  I'll fix this in CVS shortly. 
Do you maybe have a test case for this that I could add to the
regression
tests?

BTW, Mr. Terekhov does provide a good resource in his posting on this
subject.  I disagree with some points in the thread he posted, but it is
quite true that you absolutely must gaurantee that invariants hold at
the
point cond.wait() is called, and that doing so is complicated by the use
of recursive locks.  Either avoid recursive locks entirely, avoid
condition variables with recursive mutexes, or be very sure of the
design
and the state of your invariants.

-- 
William E. Kempf
Info: <http://www.boost.org>
Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl>
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