[Boost-users] [thread/condition_variable] crashes in condition variable

Subject: [Boost-users] [thread/condition_variable] crashes in condition variable
From: Dietmar Hummel (hummel_at_[hidden])
Date: 2010-07-21 04:45:26

Hi all!

I have a problem with the condition variable class. I wrote a sync 
object class (something which two threads have a reference to, the one 
is waiting on in in wait() the other will signal it with signal().

This is some pseudo code which illustrates my problem:

function doSomething()
{
        // the sync object is to keep this thread
        // waiting until the other one is done
        CPGSUSyncObject cSyncObject;

        // give a pointer of the sync object to another thread
        ...

        // at one time in the future the other thread will call
        // its signal routine which calls condition_variable::notify_all
        

        // wait until the other one has done its tasks
        cSyncObject.wait();
}

My problem (as far as I can see it) is the following:

condition_variable::notify_all() calls wake_waiters() but does further 
tasks after this call (I assume that wake_waiters() is doing the real 
signalling by the os?). But if I have the task switch fast enough, it 
may happen that my doSomething() method runs out of scope deleting 
cSyncObject which is itself deleting the condition_variable. So the 
vector iteration code in condition_variable::notify_all() crashes 
because the object is already destroyed...

Any help or good hints are appreciated...

Regards
Dietmar