Date: Fri, 25 Aug 2000 06:24:09 -0700 From: "'Alfred Perlstein'" <bright@wintelcom.net> To: "Yevmenkin, Maksim N, CSCIO" <myevmenkin@att.com> Cc: core-ix@hushmail.com, freebsd-hackers@FreeBSD.ORG Subject: Re: Preventing zombies to occure Message-ID: <20000825062409.O1209@fw.wintelcom.net> In-Reply-To: <E598F159668DD311B9C700902799EAF44734E5@njb140po01.ems.att.com>; from myevmenkin@att.com on Fri, Aug 25, 2000 at 08:58:28AM -0400 References: <E598F159668DD311B9C700902799EAF44734E5@njb140po01.ems.att.com>
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* Yevmenkin, Maksim N, CSCIO <myevmenkin@att.com> [000825 05:59] wrote:
> >
> > [snip]
> >
> > If a parent that has zombie children exits the kernel will attach them
> > to init (I haven't checked, but this is the common unix solution).
> > init will be calling waitpid to clear zombies automagically.
> >
> > So this sorta already happens. :)
>
> two ways:
>
> first:
>
> something like
>
> SIGCHLD_handler(int)
> {
> while (waitpid(-1, NULL, 0))
> ;
> }
This could be wrong if:
[EINTR] The call was interrupted by a caught signal, or the
signal did not have the SA_RESTART flag set.
more proper (paraniod) would be:
int
sigchld_handler(int)
{
while (waitpid(-1, NULL, 0) || errno == EINTR)
;
}
> you need to handle SIGCHLD, otherwise you will have zombies.
>
> second:
>
> use SA_NOCLDWAID flag in sigaction(2)
> in this case ``init'' will be responsible for zombie process
typo: should be 'SA_NOCLDWAIT'.
Sorry to pick, but one must be careful.
--
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."
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