通过使用互斥量可以完成多线程间对变量的互斥访问。主要函数如下：
函数成功执行后，互斥锁被初始化为未锁住态。
当pthread_mutex_lock()返回时，该互斥锁已被锁定。线程调用该函数让互斥锁上锁，如果该互斥锁已被另一个线程锁定和拥有，则调用该线程将阻塞，直到该互斥锁变为可用为止。
int pthread_mutex_lock(pthread_mutex_t *mutex);
在成功完成之后会返回零。其他任何返回值都表示出现了错误。
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>
#include <iostream>
#include <sys/syscall.h> /* 获得线程ID*/
using namespace std;
#define NUM_Thread 6
int iThread_index;
//获得线程ID
pid_t gettid(void)
{
return syscall(SYS_gettid);
}
//线程调用函数
void *thread_func(void *arg);
//线程互次变量
pthread_mutex_t work_mutex;
int main()
{
int res;
pthread_t a_thread[NUM_Thread];
pthread_mutex_init(&work_mutex,NULL);
void *thread_result;
iThread_index = 0;
for(int iIndex = 0; iIndex < NUM_Thread; iIndex ++)
{
//创建线程
res = pthread_create(&a_thread[iIndex],NULL,thread_func,(void *)&iThread_index);
if(0 != res)
{
perror("create thread failed\n");
exit(-1);
}
}
printf("Waiting for thread to finish\n");
for(int iIndex = 0; iIndex < NUM_Thread; iIndex++)
{
//等待线程结束
res = pthread_join(a_thread[iIndex],&thread_result);
if(0!= res)
{
printf("the %d thread failed\n",iIndex);
}
}
pthread_mutex_destroy(&work_mutex);
printf("press any key exit\n");
char c = getchar();
c = getchar();
}
void *thread_func(void * arg)
{
printf("thread: %5u do something\n", gettid());
int rand_num =rand()%10;
sleep(rand_num);
printf("thread: %5u finish do something\n", gettid());
//互次变量加锁
pthread_mutex_lock(&work_mutex);
int my_num = iThread_index;
printf("the %d thread enter func\n",my_num);
rand_num =rand()%10;
sleep(rand_num);
printf("the %d thread exit func\n",my_num);
iThread_index++;
//互次变量解锁
pthread_mutex_unlock(&work_mutex);
pthread_exit(NULL);
}
结果
administrator@ubuntu:~/桌面/Java/thread$ g++ threadmutex.cpp -o threadmutex -lpthread
administrator@ubuntu:~/桌面/Java/thread$ ./threadmutex thread: 3888 do something
thread: 3892 do something
thread: 3890 do something
thread: 3889 do something
Waiting for thread to finish
thread: 3891 do something
thread: 3893 do something
thread: 3888 finish do something
the 0 thread enter func
thread: 3891 finish do something
thread: 3890 finish do something
thread: 3893 finish do something
thread: 3892 finish do something
thread: 3889 finish do something
the 0 thread exit func
the 1 thread enter func
the 1 thread exit func
the 2 thread enter func
the 2 thread exit func
the 3 thread enter func
the 3 thread exit func
the 4 thread enter func
the 4 thread exit func
the 5 thread enter func
the 5 thread exit func
press any key exit
本文出自 “风清扬song” 博客，请务必保留此出处http://2309998.blog.51cto.com/2299998/1394544