pthread.c

#include <pthread.h>
#include <stdio.h>
#include <assert.h>

pthread_mutex_t cntr_mutex = PTHREAD_MUTEX_INITIALIZER;

long protVariable = 0L;

void *myThread(void *arg)
{
    int i, ret;
    for (i=0; i<10000;i++){
        ret = pthread_mutex_lock(&cntr_mutex);
       assert(ret==0);
       protVariable ++;
       ret = pthread_mutex_unlock( &cntr_mutex);
       assert(ret==0);

    }
    pthread_exit(NULL);
}


#define MAX_THREADS 10


int main()
{
    int ret, i ;
    pthread_t threadIds[MAX_THREADS];
    for(i=0;i< MAX_THREADS; i ++) {
        ret= pthread_create(& threadIds[i], NULL, myThread, NULL);
        if(ret != 0){
            printf("Error creating thread %d \n", (int) threadIds[i]);
        }
 
    }
    for(i=0; i< MAX_THREADS; i ++) {
        printf("before join thread %d \n", (int)threadIds[i]);
        ret = pthread_join(threadIds[i], NULL);
        if(ret != 0)
            printf("Error joining thread %d \n", (int)threadIds[i]);

        printf("after join thread %d \n", (int)threadIds[i]);
    }
        
    printf("The protected variable value is %d\n", protVariable);
    ret = pthread_mutex_destroy( &cntr_mutex);
    if(ret != 0)
        printf("Couldn't destroy the mutex \n ");
    return 0;


}