pthread_exit在main线程中的用处
在main线程中调用pthread_exit
会起到只让main线程退出,但是保留进程资源,供其他由main创建的线程使用,直至所有线程都结束,但在其他线程中不会有这种效果
to allow other threads to continue execution, the main thread should terminate by calling pthread_exit() rather than exit(3).
it's fine to use pthread_exit in main. when pthread_exit is used, the main thread will stop executing and will remain in zombie(defunct) status until all other threads exit.
if you are using pthread_exit in main thread, cannot get return status of other threads and cannot do clean-up for other threads (could be done using pthread_join(3)). also, it's better to detach threads(pthread_detach(3)) so that thread resources are automatically released on thread termination. the shared resources will not be released until all threads exit.
在win10的wls中,使用g++ -g -pthread pthreadtest.cpp
编译如下代码,然后执行,会发现main退出之后,pthread1和pthread2还是会继续跑。而,如果在mian中,注释pthread_exit(null);
,使用return退出,则pthread1和pthread2也会随着退出。
#include <pthread.h> #include <iostream> #include <unistd.h> using namespace std; //int a = 1, b = 2; void * fun(void * param){ int *ptr = (int *)param; while(true){ cout <<"from pthread " << (*ptr) << endl; sleep(2); } return null; } int main(){ int a = 1, b = 2; pthread_t t1, t2; pthread_create(&t1, null, fun, &a); pthread_create(&t2, null, fun, &b); int c = 10; while(--c > 0){ cout << "from main " << c << endl; sleep(1); } cout << "main pthread_exit \n"; pthread_exit(null); cout << "main return \n"; return 0; }
使用pthread_exit(null);
, 输出结果如下:
上一篇: linux每日命令(32):gzip命令
下一篇: c++学习笔记(一)