Pthreads and classes

I have made a Queue-class containing storage vectors and mutexes. To initialise the queue, a thread needs to be started. To make sure the thread is started correctly, the constructor waits for a signal. The thread function is a friend of the Queue-class. However, the signal is not registered when sent by the thread function. Why?

Queue::Queue()
{
    (...)
    pthread_mutex_init( &mutex_cond_init, NULL);
    Q_ready = false;
    (...)
    pthread_create(&thread_ID, NULL, Queue_function, this);

    pthread_mutex_lock(&mutex_cond_init);
    while(!Q_ready)
    {
        cout << "waiting" << endl;
        pthread_cond_wait(&cond_init,&mutex_cond_init);
        cout << "got signal" << endl;
    }
    pthread_mutex_unlock(&mutex_cond_init);
    cout << "Queue open." <<endl;
}


void * Queue_function (void*arg)
{
    (...)
    Queue * S = (Queue*) arg;

    pthread_mutex_lock(&(*S).mutex_cond_init);
     (*S).Q_ready = true;

     pthread开发者_StackOverflow_cond_signal(&(*S).cond_init);
    pthread_mutex_unlock(&(*S).mutex_cond_init);
    (...)
}

any help would be appreciated

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Have you initialised cond_init? Your code only shows initialisation of mutex_cond_init.