"[notice] child pid XXXX exit signal Segmentation fault (11)" in apache error.log [closed]

Question

I am using Apache/PHP/MySQL stack.
Using as framework CakePHP.

Every now and then I get a blank white page. I can't debug it through Cake, so I peek in the apache error.log and here's what I get:

[Wed Oct 12 15:27:23 2011] [notice] child pid 3580 exit signal Segmentation fault (11) [Wed Oct 12 15:27:34 2011] [notice] child pid 3581 exit signal Segmentation fault (11) [Wed Oct 12 15:30:52 2011] [notice] child pid 3549 exit signal Segmentation fault (11) [Wed Oct 12 16:04:27 2011] [notice] child pid 3579 exit signal Segmentation fault (11) zend_mm_heap corrupted [Wed Oct 12 16:26:24 2011] [notice] child pid 3625 exit signal Segmentation fault (11) [Wed Oct 12 17:57:24 2011] [notice] child pid 3577 exit signal Segmentation fault (11) [Wed Oct 12 17:58:54 2011] [notice] child pid 3550 exit signal Segmentation fault (11) [Wed Oct 12 17:59:52 2011] [notice] child pid 3578 exit signal Segmentation fault (11) [Wed Oct 12 18:01:38 2011] [notice] child pid 3683 exit signal Segmentation fault (11) [Wed Oct 12 22:20:53 2011] [notice] child pid 3778 exit signal Segmentation fault (11) [Wed Oct 12 22:29:51 2011] [notice] child pid 3777 exit signal Segmentation fault (11) [Wed Oct 12 22:33:42 2011] [notice] child pid 3774 exit signal Segmentation fault (11) 

What is this segmentation fault, and how can I fix it?

UPDATE:

PHP Version 5.3.4, OSX local development Server version: Apache/2.2.17 (Unix) CakePhp: 1.3.10 

Answer 1

Attach gdb to one of the httpd child processes and reload or continue working and wait for a crash and then look at the backtrace. Do something like this:

$ ps -ef|grep httpd 0     681     1   0 10:38pm ??         0:00.45 /Applications/MAMP/Library/bin/httpd -k start 501   690   681   0 10:38pm ??         0:00.02 /Applications/MAMP/Library/bin/httpd -k start 

...

Now attach gdb to one of the child processes, in this case PID 690 (columns are UID, PID, PPID, ...)

$ sudo gdb (gdb) attach 690 Attaching to process 690. Reading symbols for shared libraries . done Reading symbols for shared libraries ....................... done 0x9568ce29 in accept$NOCANCEL$UNIX2003 () (gdb) c Continuing. 

Wait for crash... then:

(gdb) backtrace 

Or

(gdb) backtrace full 

Should give you some clue what's going on. If you file a bug report you should include the backtrace.

If the crash is hard to reproduce it may be a good idea to configure Apache to only use one child processes for handling requests. The config is something like this:

StartServers 1 MinSpareServers 1 MaxSpareServers 1