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

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
Solution

  • 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