Setting coredumpsize on a running process?

[Ivan Voras]

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.