c - waitid会消耗SIGCHLD吗？

Question

waitid/waitpid 是否会消耗任何待处理的 SIGCHLD？

例如，如果一个线程调用 waitid，而另一个线程调用 sigwaitinfo 或从 signalfd 读取，我是否可以假设这两个调用都返回正确的数据子进程何时终止？

Answer 1

找到https://lkml.org/lkml/2009/1/10/181 :

That notification only tells us that at least one process has died; SIGCHLD may only be pending once at a time. If further children die before we clear the signal, nothing will happen. ... Because it only tells us that at least one process has died, we have to call waitpid() repeatedly until we have exhausted the wait queue.

~~Calling waitpid() does not clear the pending signal.~~

Manpages 没有提到“等待队列”，但它解释了一些事情。