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From <>
Subject Re: [PATCH] screw up prefork even more
Date Wed, 13 Jun 2001 15:53:35 GMT

> This goes a ways towards getting SIGWINCH and SIGHUP to do something.
> I'm pretty sure that Ryan disagrees with the path I took for SIGHUP,
> which is to kill everybody we can with the pod (since that is the most
> clean and reliable mechanism we have) and let
> ap_reclaim_child_processes() handle the stragglers.

You can't use the pod to gracelessly shutdown the child processes.  It
doesn't do that.  The pod will only work for graceful shutdowns.

> With this patch, SIGWINCH and SIGHUP basically work for me on a
> particular machine :)

Does SIGHUP actually do a graceless shutdown on a heavily loaded machine?

> There are surely other issues.  I didn't understand Ryan's changes to
> prefork signalling when he added the pod (other than the fact that
> SIGHUP and SIGWINCH no longer caused a restart) so I don't feel to bad
> about still being in the dark.
> I don't currently know how to proceed further with this until there is
> some agreement about how a non-graceful restart will be implemented.

There are only two options for gracelessly killing a child process, that I
know of.

1)  Use signals.

2)  Have a thread that is specifically used to listen for some other
out-of-band communication.

Since we are in an MPM that doesn't have threads, signals are the only way
I know of to implement a graceless shutdown.  The pod will not be able to
do this.


Ryan Bloom               
406 29th St.
San Francisco, CA 94131

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