等待线程终止工作，然后在收到SIGINT或SIGTERM（C中的Posix线程）后关闭服务器

Question

I'm developing a client / server in C using pthread.

It's a card game where server is the dealer between two clients that play.

I have this situation

server.c :

main:

• int main (int argc, char * argv[])

  using as a thread dispatcher for listening eventually entering connection on accept

• pthread_create(&sig_thread, NULL, &thread_signal_handler, &server_Socket );

  thread to catch signals (maskered conveniently) created inside main function

• pthread_create(&tid[i++], NULL, &worker, (void*) arr_args)

  every client is associated to a thread created ( tid is the array of thread ID)

• pthread_join(sig_thread, NULL)

  to join thread for signals

• pthread_join(tid[i], NULL)

  to join thread created for every client connected.

worker:

• void * worker(void * args)

  do his job and terminated

thread signal handler:

• void * thread_signal_handler(void * arg)

void * thread_signal_handler(void * arg) {

  sigset_t set; int sig, n; int * socket = (int*) arg; sigemptyset(&set); sigaddset(&set, SIGINT); sigaddset(&set,SIGTERM); while (server_UP) { /* wait for a signal */ if (sigwait(&set, &sig)) perror("Sigwait"); /* received SIGINT or SIGTERM - closing server */ if ((sig == SIGINT || sig == SIGTERM)) { printf(TERM_SERVER"\\n"); server_UP = 0; /* global variable */ /* close socket blocked on MAIN */ shutdown( *socket, SHUT_RDWR ); } return (void *) EXIT_SUCCESS; 

}

In this way, the signal is catched well and the server is terminated immediately. I need, if there are matches in progress, to waiting that all the workers finish their jobs properly, so I want to know how to say to thread handler "did you receive a SIGINT (or SIGTERM)? Ok, waiting the termination of all workers".

Any suggests? If you need more code, i'll edit this post.

Answer 1

When you create them you can save all of the threads in an array or a list and at the end call pthread_join() on all of them.

while (pthread_list) {
    pthread_join(pthread_list->th_id, NULL);
    pthread_list = pthread_list->next;
}

If you don't want to keep track of all threads you can keep a count of running threads, increment it before calling pthread_create, decrement the count as each thread finishes.

Then in the handler you'll sleep for some seconds iteratively until the count becomes 0.