Question

我正在尝试创建一个程序，创建3个线程threa1 thread2和thread3 thread1打印thread1 5次，thread2打印thread2 5次，thread3打印thread3 5次我想使用互斥锁来获得此输出

thread1
thread1
thread1
thread1
thread1
thread2
thread2
thread2
thread2
thread2
thread3
thread3
thread3
thread3
thread3

我该怎么做？

Answer 1

这是一个解决方案：

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

#define MAX_PRINT 5
#define MAX_THREAD 3

static pthread_mutex_t mThread[MAX_THREAD] = {PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER};

void * start_thread(void * arg)
{
    int thNb = *((int*)arg);
    int i = 0;

    pthread_mutex_lock(&mThread[thNb]);

    for (i = 0; i < MAX_PRINT; i++) {
        fprintf(stdout, "thread%d\n", thNb);
    }

    pthread_mutex_unlock(&mThread[thNb]);

    return NULL;
}


int main()
{
    pthread_t thread[MAX_THREAD];
    int arg[MAX_THREAD];
    int i = 0;

    printf("Init Mutex for all threads ...");
    for (i = 0; i < MAX_THREAD; i++) {
        pthread_mutex_lock(&mThread[i]);
    }
    printf("OK\n");

    printf("Creating threads ...");
    for (i = 0; i < MAX_THREAD; i++) {
        arg[i] = i;
        pthread_create(&thread[i], NULL, &start_thread, &arg[i]);
    }
    printf("OK\n");

    printf("::::::::::::::::: OUTPUT THAT YOU WANT :::::::::::::::::::::: \n");
    for (i = 0; i < MAX_THREAD; i++)
    {
        pthread_mutex_unlock(&mThread[i]);
        pthread_join(thread[i], NULL);
    }


    return 0;
}

使用以下方式编译：

gcc -D_REENTRANT -lpthread main.c

使用Mutex序列化POSIX线程

1 个答案: