Got some excellent advice today on bug hunting PHP segfaults from Brian Shire. You can use GDB to inspect php internal variables to produce a readable backtrace that looks something like
(gdb) zbacktrace
[0xbfec1c84] unsetMap() /path/CometSimulatorServer.class.php:144
[0xbfec21b4] unsetMap() /path/CometSimulatorAssistant.class.php:153
[0xbfec23d4] merge() /path/CometSimulatorMerge.class.php:34
[0xbfec2478] process()
[0xbfec2704] call_user_func_array() /path/CometPacket.class.php:81
[0xbfec2bf4] process() /path/PacketHandler.class.php:77
[0xbfec3334] process() /path/MessagePump.class.php:84
[0xbfec35e4] recv() /path/MessagePump.class.php:56
[0xbfec3ab4] task() /path/Event.class.php:190
[0xbfec4414] run() /path/LoopScheduler.class.php:113
[0xbfec5354] dispatch() /path/cometd.php:161
Basic process
ulimit -c unlimited # run your script
gdb /path/to/php/binary -c [corefile] -x [debug-script]
gdb debug functions
