Re: [Boost-users] [Thread]Deadlock using shared_mutex with unique_lock

Subject: Re: [Boost-users] [Thread]Deadlock using shared_mutex with unique_lock
From: Anthony Williams (anthony.ajw_at_[hidden])
Date: 2008-09-05 16:48:02

Stanislav Stoyanov <stystoyanov_at_[hidden]> writes:

> I am trying to use shared_mutex with unique_lock but my program blocks.
> I am using boost 1.35. My compiler is MSVC 8.0.50727.762 and my OS is
> Windows 2000.
> Here is a minimal code to reproduce the problem:
>
> #include "boost/thread.hpp"
> #include "boost/thread/shared_mutex.hpp"
> #include "boost/bind.hpp"
>
> class Executor {
> public:
>    void run() {
>        boost::unique_lock<boost::shared_mutex> lock(theMutex);
>        boost::thread::sleep(boost::get_system_time() +
> boost::posix_time::millisec(30));
>    }
> private:
>    boost::shared_mutex theMutex;
> };
>
> void main() {
>    Executor ex;
>    boost::thread_group group;
>    for(int i=0; i<200; i++) {
>        group.create_thread(boost::bind(&Executor::run, &ex));
>    }
>    group.join_all();
> }
>
> The program blocks during the call of group.join_all(). According to
> the Boost.Thread documentation,
> unique_lock<boost::shared_mutex> lock(theMutex) acquires exclusive
> ownership of theMutex. Therefore,
> I expect that the behaviour of boost::unique_lock<boost::shared_mutex>
> lock(theMutex); is the same as if a
> boost::mutex is used. Is my assumption correct or am I missing something?

Your code looks right at first glance, and I agree there's a
problem. I'm looking into it.

Anthony
-- 
Anthony Williams            | Just Software Solutions Ltd
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