本文主要介绍C/C++中多线程编程的方法。
#include <pthread.h>
int pthread_create(pthread_t * thread, const pthread_arrt_t* attr, void*(*start_routine)(void *), void* arg);
void pthread_exit(void * retval);
void pthread_join(pthread_t thread,void ** retval);
pthread_mutex_init(&mutex1,NULL); // 初始化互斥锁
pthread_mutex_destroy(&mutex1); // 释放锁资源
pthread_mutex_lock(&mutex1); // 加锁
pthread_mutex_unlock(&mutex1); // 去锁
实例如下
#include <pthread.h>
#include <stdio.h>
pthread_mutex_t mutex1;
void *foo(void *arg)
{
int* id = (int*) arg;
pthread_mutex_lock(&mutex1);
for (int i = 0; i < 5; ++i){
sleep(1);
printf("Myid %d\n", *id);
}
pthread_mutex_unlock(&mutex1);
}
int main()
{
pthread_t id[4];
pthread_mutex_init(&mutex1,NULL);
for (int i = 0; i < 4; ++i)
pthread_create(&id[i],NULL,foo,&i);
for (int i = 0; i < 4; ++i)
pthread_join(&id[i],NULL);
for (int i = 0; i < 4; ++i)
pthread_exit(&id1);
pthread_mutex_destroy(&mutex1);
}
编译指令添加-lpthread
C++11中添加了标准库的多线程支持
#include <iostream>
#include <thread>
using namespace std;
void exec(int n){
cout << "thread" << n << endl;
}
int main(){
thread myThread[4];
for (int i = 0; i < 4; ++i)
myThread = thread(exec,i);
for (int i = 0; i < 4; ++i)
myThread[i].join();
}
当要传共享变量/引用时采用std::ref()实现。
加互斥锁(mutex)需要添加头文件<mutex>，然后在全局变量声明一个锁，在函数内部打开lock_guard。
std::mutex g_display_mutex;
thread_function()
{
std::lock_guard<std::mutex> guard(g_display_mutex);
std::thread::id this_id = std::this_thread::get_id();
std::cout << "From thread " << this_id << endl;
}
这是C++11比较支持的方式，lock_guard的作用域即为它的生存期。
对于多线程程序，编译时还是要添加-pthread指令