Re: Question on C++ Thread Class and inheritance/polymorphism with POSIX pthread

On Oct 27, 11:43 am, Ian Collins <ian-n...@hotmail.com> wrote:


So close, but not quite. Actually, 'main' can't return because the
destructor calls 'pthread_join'.

In fact, his problem is that he calls 'pthread_join' in the
destructor. You can't do that. In fact, he can replicate his problem
without using threads at all. Consider:

class Thread
{
public:
       Thread(void);//constructor
       virtual ~Thread();//distructor
       virtual void run(void);
};

Thread::Thread()
{
}

Thread::~Thread()
{
 run();
}

void Thread::run()
{
 printf("Base\n");
}

class MyThread : public Thread
{
public:
virtual void run(void);
};

void MyThread::run(void)
{
printf("Derived\n");
}

int main(void)
{
 MyThread mt;
}

In simplest terms, he has a race condition. His 'main' function
destroys an object (his thread object) while another thread (the newly-
created thread) is, or might be, using it. Calling 'pthread_join' in
the destructor is nonsense.

DS