c_cpp C - 线程

Posted 2021-05-14

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>

#define NLOOP 5000

int counter;
pthread_mutex_t counter_mutex = PTHREAD_MUTEX_INITIALIZER;

void *doit(void *);

int main(int argc, char **argv)
{
    pthread_t tidA, tidB;

    pthread_create(&tidA, NULL, doit, NULL);
    pthread_create(&tidB, NULL, doit, NULL);

    /* wait for both threads to terminate */
    pthread_join(tidA, NULL);
    pthread_join(tidB, NULL);

    return 0;
}

void *doit(void *vptr)
{
    int i, val;

    /* Each thread fetches, prints, and increments the counter NLOOP times.
     * The value of the counter should increase monotonically.
     */

    for (i = 0; i < NLOOP; i++){
        pthread_mutex_lock(&counter_mutex);

        val = counter;
        printf("%x: %d\n", (unsigned int)pthread_self(), val + 1);
        counter = val + 1;

        pthread_mutex_unlock(&counter_mutex);
    }

    return NULL;
}