Hi Piotr,

The (grand)child process does some things asynchronously from the
module and I'm basically using the double fork to know when the
grandchild is up and running (when execv() returns, I know its
initialized and running). I then make a unix socket connection to it
and pass some data back and forth. The (grand)child SIGALRM's and
exits after a timeout period (60 seconds) unless it's reattached to
and reused. Curiously, if I bring up the child manually (nginx module
not doing the fork/exec) then everything works fine. Also if a second
nginx worker attaches subsequently, it works. It is only the act of
the fork which seems to invoke the problem. It's almost as if nginx
is doing a wait() for the child before closing the request, although I
know the child has been reaped earlier and the grandchild is now a
child of init.

Like I said, I only noticed the behavior when using http proxy
caching, so the problem has existed for me all along without my being
aware of it.

Brian

2009/12/21 Piotr Sikora <piotr.sikora@frickle.com>:
> Hi Brian,
> it's hard to tell what goes wrong just from your description, but could you
> explain what's the reason behind double-fork() & reparenting child process?
>
> I've recently made a module (to be released *soon*) which also fork()s and I
> didn't notice such behavior.
>
> Best regards,
> Piotr Sikora < piotr.sikora@frickle.com >
>
>
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> nginx@nginx.org
> http://nginx.org/mailman/listinfo/nginx
>

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