Setting coredumpsize on a running process?

[Fabian Keil]

Ivan Voras <ivoras at freebsd.org> wrote:

> On 18 October 2011 16:43, Jeremy Chadwick <freebsd at jdc.parodius.com> wrote:
> > On Tue, Oct 18, 2011 at 04:32:11PM +0200, Ivan Voras wrote:
> >> I have PHP executing as fastcgi via the mod_fcgid module in Apache. I
> >> suspect there is a bug in PHP or one of its extensions which causes it
> >> to crash with sigsegv, but I cannot get any coredumps. I suspect
> >> something is setting coredumpsize to 0 - either Apache, mod_fcgid or PHP.
> >>
> >> So the question is: is there a way to set coredumpsize on a running
> >> process, with the intention of getting a core dump when it crashes? I
> >> already tried setting CoreDumpDirectory in Apache and also configuring
> >> apache22limits_args in /etc/rc.conf but without effect.
> >
> > I ended up solving this on a machine where coredumps with Apache + PHP
> > were highly common by setting sysctl kern.corefile to
> > /var/cores/%P.%N.core, then made sure the /var/cores directory was
> > root:wheel, perms 1777.  Otherwise I could not get a coredump.
> > apache22limits_enable did not help either, nor did CoreDumpDirectory.
> 
> > Having fun yet?
> 
> Oh, I have years and years of fun debugging PHP, in one way or the other :)
> 
> Your suggestion for setting core dump directory explicitely helped;
> now it looks like I've hit an infinite recursion / stack eating bug
> somewhere in PCRE...
> 
> #1703 0x0000000805d5c72e in match () from /usr/local/lib/libpcre.so.0
> #1704 0x0000000805d5b4f0 in match () from /usr/local/lib/libpcre.so.0
> #1705 0x0000000805d5c72e in match () from /usr/local/lib/libpcre.so.0
> #1706 0x0000000805d5b4f0 in match () from /usr/local/lib/libpcre.so.0
> 
> However, I'm drawing the line at debugging PCRE, this will go into the
> "don't do that" category.

There's a fair chance that this isn't a bug in pcre,
but the result of a poorly written expression.

You may want to have a look at pcrestack(3).

Fabian
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 196 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20111018/2c39927c/signature.pgp