如何检查当前是否有任何线程正在运行
我知道有一个用于多进程的
waitpid(-1,WNOHANG,NULL)
非阻塞函数调用来检查当前是否有任何子进程正在工作
但是是否有任何类似的 lib 函数来检查多线程？
我想要做的就是检查当前是否有任何线程，如果没有则重置一些全局值。
I know there is one for multi processes
waitpid(-1,WNOHANG,NULL)
that is non-blocking function call to check if there is any child process currently working on
But is there any similar lib function to check for multithread?
All i want to do is check if there is any thread currently on, if not reset some global values.
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错误。这是一个检查是否有任何子进程尚未终止的调用。它不仅检查而且还收获终止的孩子（如果有的话）。否则，孩子们可能会处于任何可能的状态，比如陷入僵局（在我的书中，这远非有效）。
也许你应该在这里发帖作为一个问题，问你为什么要这样做。听起来你做了一些非常错误的事情。
如果您还没有为您的线程执行 pthread_join() ，则意味着您的线程已经执行 pthread_detach() 。如果添加到线程 pthread_detach() 没有问题，我认为向线程添加一些额外的代码以识别它们已经（几乎）终止（例如 sem_post()）是没有问题的，以便 main() 可以注意到线程已终止（例如通过调用 sem_trylock()）。
如果可移植性不是必需的，那么还可以尝试定期查询进程的操作系统线程数。
尽管在程序中存在一些具有未定义生命周期的线程，并且与主线程没有任何适当的同步，但在我看来仍然是错误的。
Wrong. That is a call to check if there is any child process not yet terminated. And it not only checks but also reaps a terminated child, if any. Children might be otherwise in any possible state, like hanging in a deadlock (what on my book is far from being working).
Probably you should post here as a question why you want to do it. It sounds that you do something terribly wrong.
If you do not do already pthread_join() for your threads, that means that your threads already do pthread_detach(). If you had no problems adding to your threads pthread_detach() I think there would be no problem to add some extra code to threads to identify that they have (almost) terminated (e.g. sem_post()) so that main() can notice that a thread had terminated (e.g. by calling sem_trylock()).
If portability isn't a requirement, then one can also try query OS number of threads of the process periodically.
Though it is still IMO wrong to have in a program some threads, with undefined life cycle, without any proper sync with main thread.
您可以只保存线程的句柄并使用一个函数来检查它是否仍在运行。我不确定是否有功能，但这应该可以。
You could just save the handle of a thread and have a function to check if it is still running. I'm not sure if theres a function but this should work.
pthread_kill(pid, 0) 其中 pid 是 pthread_create 返回的线程 ID，可以告诉您线程是否仍处于活动状态。 （这就是我对你问题的理解）
如果线程仍然存在，则返回 0，否则返回错误代码。
pthread_kill(pid, 0) where pid is the thread id that pthread_create has returned can tell you if a thread is still alive. (That is how I understand your question)
It returns 0 if the thread is still alive and an error code otherwise.
我问自己一些非常相似的问题：
POSIX用于列出进程中运行的所有 pthread 的 API 调用
在您的情况下，我将直接结束
ps -eLF。I asked myself something quite similar:
POSIX API call to list all the pthreads running in a process
In your case I would just wrapped up
ps -eLF.