- use
strace, truss, kdump/ktrace
on httpd children and you will probably see the php filename causing the issue
- Set CoreDumpDirectory on one of
the crashing systems
- if possible, choose only one system since writing core files can cause a lot of load
- Make sure you have debugging symbols. On Redhat/CentOS you will need to install -debuginfo RPM (for apache/httpd AND php/mod_php)
- Run
gdb httpd core.1234
- Now run
bt
- and examine the
opline
tips for php/gdb
print *opline
print opline->op2.u.constant.value.str.val
print opline->op1.u.constant.value.str.val
In my case (and the one below) op1 started with a null byte, so you needed to run:
print opline->op1.u.constant.value.str.val+1
And you will get the php file name and, probably, the function which is causing the issue.