Linux multi-threaded mutex-ticketing

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <pthread.h>int ticket_cnt =     20;    /* Total 20 tickets */typedef struct tag{int s_id; pthread_mutex_t *s_p;}    data,*pdata;void* handler (void *arg) {int id = ((pDATA) arg)->s_id;    pthread_mutex_t *p_mutex = ((PDATA) arg), s_p;    printf ("A window on!:%d \ n", id);        while (1) {pthread_mutex_lock (P_mutex); if (ticket_cnt = = 0) {printf ("Ticket out!            \ n ");            Pthread_mutex_unlock (P_mutex);            Free ((PDATA) arg);        Return (void*) 0;        }--ticket_cnt;        Sleep (rand ()%3 + 1); printf ("Window:%d:a ticket sold.        Left:%d \ n ", id,ticket_cnt);        Pthread_mutex_unlock (P_mutex); Sleep (rand ()% 3 + 1);    /* If you do not sleep, the lock will always be occupied by this executed thread */}}int main (int argc, char *argv[]) {Srand (Getpid ());    pthread_mutex_t Mutex;    Pthread_mutex_init (&mutex, NULL); int thd_cnt = atoi (argv[1]); /* Enter the number of ticket windows from the command line */PThread_t *tds = (pthread_t*) calloc (thd_cnt,sizeof (pthread_t));    int index;        for (index = 0; index < thd_cnt; index++) {PDATA p = (PDATA) calloc (1,sizeof (DATA));        p->s_id = index;        p->s_p = &mutex;    Pthread_create (TDS + index, Null,handler, (void*) p);    } printf ("joining...\n");    for (index = 0; index < thd_cnt; index++) {pthread_join (tds[index],null);    } Pthread_mutex_destroy (&mutex); return 0;}

Linux multi-threaded mutex-ticketing