子进程可以去＆LT;＆倒闭GT;没有它的父进程要死了吗？ [英] Can a child process go <defunct> without its parent process dying?

问题描述

杀 - 它杀掉该进程马上

我发现我的回答，我设置了 SIGCHLD 并介绍了等的信号处理程序的处理程序。这样一来，当父进程杀一个子进程，这个处理程序被调用，它调用等待来的收获的孩子。 - 动机是清除进程表项

I found my answer and I set up a signal handler for SIGCHLD and introduced wait in that handler. That way, whenever parent process kills a child process, this handler is called and it calls wait to reap the child. - motive is to clear process table entry.

我仍然看到一些孩子去处理了几秒钟，即使没有它的父进程奄奄一息。 - 这是怎么的可能

I am still seeing some child processes going for a few seconds even without its parent process dying. - how is this possible?

我通过 PS 看到这个。 precisely PS -o用户，PID，PPID，命令-ax 和greping的父进程，子进程和解散。

I am seeing this via ps. Precisely ps -o user,pid,ppid,command -ax and greping for parent process, child process and defunct.

推荐答案

一个过程进行解散（僵尸），立即在退出（从信号，打电话退出，回报从主，等等）。它停留僵尸，直到等'由其父D ON。

A process goes defunct (zombie) immediately upon exiting (from a signal, call to exit, return from main, whatever). It stays zombie until wait'd on by its parent.

所以，所有的进程至少短暂成为退出时的僵尸。

So, all processes at least briefly become zombies upon exit.

如果父进程需要多一点（因为它是做其他工作，或者只是因为调度程序没有给它的CPU时间未定）之前调用等，然后你会看到一个有点僵尸。如果父永远不会调用等，那么当它最终退出，的init （PID 1）将通过其zombied的孩子，和呼叫等在他们身上。

If the parent process takes a bit (because it was doing other work, or just because the scheduler hasn't given it CPU time yet) before calling wait, then you'll see the zombie for a bit. If the parent never calls wait, then when it eventually exits, init (pid 1) will adopt its zombied children, and call wait on them.

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