Date: Fri, 29 May 2009 12:31:37 -0700 From: Alfred Perlstein <alfred@freebsd.org> To: Dag-Erling Sm??rgrav <des@des.no> Cc: Nate Eldredge <neldredge@math.ucsd.edu>, yuri@rawbw.com, freebsd-hackers@freebsd.org Subject: Re: Why kernel kills processes that run out of memory instead of just failing memory allocation system calls? Message-ID: <20090529193137.GH67847@elvis.mu.org> In-Reply-To: <863aaow866.fsf@ds4.des.no> References: <4A14F58F.8000801@rawbw.com> <Pine.GSO.4.64.0905202344420.1483@zeno.ucsd.edu> <4A1594DA.2010707@rawbw.com> <86ljoig08o.fsf@ds4.des.no> <20090528213017.GX67847@elvis.mu.org> <863aaow866.fsf@ds4.des.no>
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* Dag-Erling Sm??rgrav <des@des.no> [090529 02:49] wrote:
> Alfred Perlstein <alfred@freebsd.org> writes:
> > Dag-Erling Sm??rgrav <des@des.no> writes:
> > > Usually, what you see is closer to this:
> > >
> > > if ((pid = fork()) == 0) {
> > > for (int fd = 3; fd < getdtablesize(); ++fd)
> > > (void)close(fd);
> > > execve(path, argv, envp);
> > > _exit(1);
> > > }
> >
> > I'm probably missing something, but couldn't you iterate
> > in the parent setting the close-on-exec flag then vfork?
>
> This is an example, Alfred. Like most examples, it is greatly
> simplified. I invite you to peruse the source to find real-world
> instances of non-trivial fork() / execve() usage.
It wasn't meant to critisize, just ask a question for the specific
instance because it made me curious. I know how bad it can be with
vfork as I observed a few fixes involving mistaken use of vfork at
another job.
So yes, there's more than one way to skin a cat for this particular
example... but in practice using vfork()+exec() is hard to get right?
--
- Alfred Perlstein
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