Re: [Boost-users] [Boost-Threads] Assertion during a second call to thread::join

From: Ovanes Markarian (om_boost_at_[hidden])
Date: 2006-08-23 04:54:30

Hi!

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With Kind Regards,

Ovanes Markarian

On Wed, August 23, 2006 09:25, Aubrey, Jason wrote:
> Hi,
>
> My Environment:
>   * MSVC 8.0
>   * boost v1.33.1
>
> Using the example program below, I'm getting an assertion within boost's
> thread class during a call to join.    join() is being called twice: 1)
> in main() 2) in ~Thread().  If I remove one of the calls to join() the
> assertion goes away.  Though this example's usage seems redundant such
> behavior should be similar to the scenario of multiple threads waiting
> on the same thread via join().
>
> Help would be appreciated.
>
> Regards,
> Jason
>
> // --------------------------------- BEGIN EXAMPLE PROGRAM
> ---------------------------
> // Assertion failed: m_joinable, file
> C:\...\boost\boost_1_33_1\libs\thread\build\..\src\thread.cpp, line 223
> // Call Stack begins in the following code at the end of main() within
> ~Thread() in the call to join().
>
> #include <boost/bind.hpp>
> #include <boost/noncopyable.hpp>
> #include <boost/shared_ptr.hpp>
> #include <boost/thread/thread.hpp>
> #include <boost/thread/xtime.hpp>
>
> // This class misuses inheritance, but is provided for those
> // familiar with Java syntax that don't care
> class Thread : public boost::noncopyable
> {
> private:
>     boost::shared_ptr<boost::thread> _thread;
>
> public:
>     Thread(){}
>     virtual ~Thread() { join(); }
>
>     void join()
>     {
>         if ( _thread )
>            _thread->join();
>     }
>
>     virtual void run() = 0;
>
>     void start()
>     {
>         if ( !_thread )
>             _thread.reset( // Reference to the thread
>                 new boost::thread( // New thread of execution
>                     boost::bind(&Thread::run, this) // Functor calls
> run()
>                     ));
>     }
> };
>
> struct MyThread : public Thread
> {
>     void run() {}
> };
>
> void main()
> {
>     MyThread t;
>     t.start();
>     t.join(); // No assertion if this line is commented
>     return;
> }
>
> // --------------------------------- END EXAMPLE PROGRAM
> ---------------------------
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