CODEWITHSUNDEEP
csocketspthreadsfork
user1190650
user1190650

Reputation: 3425

creating pthreads after a fork

I am writing a C program that forks once it accepts a client connection. Once this happens, I want to spawn two threads, but I cannot seem to get this working. 

    pthread_t t1, t2;
    void *r_loop();
    void *w_loop();
    .
    .
    .

sockfd = accept(r_sockfd, (struct sockaddr *) &address, &len);
if (sockfd < 0)
    printf("Error accepting\n");

if (!fork())
{
    int r_thread = pthread_create(&t1, NULL, r_loop, NULL);
    int w_thread = pthread_create(&t2, NULL, w_loop, NULL);

    pthread_join(r_thread, NULL);
    pthread_join(w_thread, NULL);
    exit(0);
}

When I run this, the functions r_loop and w_loop don't get executed.

Upvotes: 2

Views: 496

Answers (2)

Pawel Kolodziej
Pawel Kolodziej

Reputation: 91

you should pass t1 and t2 instead of r_thread and w_thread to pthread_join().

Upvotes: 1

Jack
Jack

Reputation: 1606

The problem could be this: pthread_create() on success alwasy returns zero. You are passing to pthread_join() an incorrect value (that is zero instead of t1 and t2) making them to return immediately. Then the following exit() also kills the new starting threads

Upvotes: 5

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