几个重要的函数：

#include <pthread.h>

int pthread_mutex_init(pthread_mutex_t *restrict mutex, const pthread_mutex_t *restrict attr); //初始化mutex

int pthread_mutex_destroy(pthread_mutex_t *mutex); //如果mutex是动态分配的，则释放内存前调用此函数。

int pthread_mutex_lock(pthread_mutex_t *mutex); //加锁

int pthread_mutex_trylock(pthread_mutex_t *mutex); //若已有其他线程占用锁，则返回EBUSY，否则返回0，不阻塞。

int pthread_mutex_unlock(pthread_mutex_t *mutex); //解锁

例程：

复制代码 代码如下:

#include <stdlib.h>

#include <stdio.h>

#include <unistd.h>

#include <pthread.h>

#include <errno.h>

int a = 100;

int b = 200;

pthread_mutex_t lock;

void * threadA()

{

pthread_mutex_lock(&lock);

printf("thread A got lock!n");

a -= 50;

sleep(3); //如果不加锁，threadB输出会是50和200

b += 50; //加锁后会sleep 3秒后，并为b加上50 threadB才能打印

pthread_mutex_unlock(&lock);

printf("thread A released the lock!n");

a -= 50;

}

void * threadC()

{

sleep(1);

while(pthread_mutex_trylock(&lock) == EBUSY) //轮询直到获得锁

{

printf("thread C is trying to get lock!n");

usleep(100000);

}

printf("thread C got the lock!n");

a = 1000;

b = 2000;

pthread_mutex_unlock(&lock);

printf("thread C released the lock!n");

}

void * threadB()

{

sleep(2); //让threadA能先执行

pthread_mutex_lock(&lock);

printf("thread B got the lock! a=%d b=%dn", a, b);

pthread_mutex_unlock(&lock);

printf("thread B released the lock!n", a, b);

}

int main()

{

pthread_t tida, tidb, tidc;

pthread_mutex_init(&lock, NULL);

pthread_create(&tida, NULL, threadA, NULL);

pthread_create(&tidb, NULL, threadB, NULL);

pthread_create(&tidc, NULL, threadC, NULL);

pthread_join(tida, NULL);

pthread_join(tidb, NULL);

pthread_join(tidc, NULL);

return 0;

}