pthread_join not waiting on threads to finish

Question

I am using pthreads.h on Windows, for a simple raytracer. It seems like the main function is not waiting for the threads to finish. When I just run the program like this(I now simplified it, to just test the threads, but it still gives the error):

typedef struct {
    unsigned int id; 
} Thread_Data;

void* render_band(void* arg) {
    Thread_Data* data = (Thread_Data*)arg;
    printf("This is thread number %d", data->id);
    pthread_exit(0);
}

int main() {
    pthread_t threads[NUM_THREADS];
    Thread_Data data[NUM_THREADS];
    for (int i = 0; i < NUM_THREADS; i++) {
        data[i].id = id;

        int rc = pthread_create(&threads[i], NULL, render_band, &data[i]);
        if (rc) {
            printf("[ERROR] From pthread_create: %d\n", rc);
        }
    } 

    for (int i = 0; i < NUM_THREADS; i++) {
        int rc = pthread_join(threads[i], NULL);
        if (rc) {
            printf("[ERROR] From pthread_join: %d\n", rc);
        }
    }
}

The image won't be completed and only renders a couple of pixels. When I add a sleep however, the image does finish. Leading me to believe that pthread_join doesn't wait, even though the documentation says so. What am I missing here?

Edit: Added error checking, it returns error code 3 for the pthread_join.

Answer 1

I am sorry for wasting everbody's time. The issue ended up being the library itself. When I was looking for pthreads.h on Windows, I found some library on sourceforge. But apparently MinGW already had pthread support, and it messed everything up. So for people with the same issue, just use the one that comes with MinGW.