为什么 pthread_exit 表现得像 pthread_join？

Question

代码：

void *PrintHello(void *threadid)
{
   cout<<"Hello"<<endl;
   sleep(3);
   cout<<"Still PrintHello is alive"<<endl;
}
int main (int argc, char *argv[])
{
   pthread_t threads[NUM_THREADS];
   cout<<"Calling thread:"<<t<<endl;
   pthread_create(&threads[0], NULL, PrintHello, NULL);
   //pthread_join(threads[0],NULL);
   cout<<"Main exits"<<endl;
   pthread_exit(NULL);
}

为什么 pthread_exit(NULL) 在这里表现得像 pthread_join()？即为什么退出 main 不破坏 printHello 线程并允许它继续？

Answer 1

pthread_exit() 仅终止调用线程。因此，当您从 main() 调用它时，它会终止主线程，同时允许进程继续。这符合预期。

如果您改为调用 exit()（或通过返回隐式退出），它将终止整个过程，您将看到 printHello 也终止。

Answer 2

有很好的资源here但引用解释你的问题的部分：

Discussion on calling pthread_exit() from main():

There is a definite problem if main() finishes before the threads it spawned if you don't call pthread_exit() explicitly. All of the threads it created will terminate because main() is done and no longer exists to support the threads.

By having main() explicitly call pthread_exit() as the last thing it does, main() will block and be kept alive to support the threads it created until they are done.

为什么 pthread_exit 表现得像 pthread_join？

Why pthread_exit acts like pthread_join?

c

c++

pthreads

pthread-join

pthread-exit