Re: [Boost-users] [Boost.Thread] self deadlocking issue

From: Anthony Williams (anthony_w.geo_at_[hidden])
Date: 2007-08-03 03:56:20

Cheng Lian <rhythm.mail_at_[hidden]> writes:

> Hi, all
>
> I was debugging a buggy program which could be simplified as below:
>
> #include <boost/thread.hpp>
>
> using namespace boost;
>
> mutex m;
>
> void f() {
>     mutex::scoped_lock lock( m );
> }
>
> int main() {
>     mutex::scoped_lock lock( m );
>     f();
>     return 0;
> }
>
> I think this would definitely self deadlock and the program should be
> waiting forever. And my Debian Linux box proved that true. But on my XP
> (with SP2) box, the program didn't dead lock and everything pass through!
> Seems that on Win32 platform, the mutex is recursive? I checked the code and
> only CRITICAL_SECTION related is found around the lock/unlock lines. But I
> think CRITICAL_SECTION itself is not recursive. Then why? Thanks for
> response.

Windows CRITICAL_SECTIONs are recursive. The 1.34 boost mutex is based on a
CRITICAL_SECTION, so is therefore also recursive on Windows. The 1.35 mutexes
will not be recursive on Windows.

Anthony
-- 
Anthony Williams
Just Software Solutions Ltd - http://www.justsoftwaresolutions.co.uk
Registered in England, Company Number 5478976.
Registered Office: 15 Carrallack Mews, St Just, Cornwall, TR19 7UL