I'm running PHP3 compiled with mysql support as an
Apache (1.3.9) module. It sometimes crashes on large
scripts containing multiple classes and nested includes and requires.

When I recompiled it with -enable-debug and ElectricFence,
gdb httpd core says following:

(gdb) where
#0  0x80e3fec in slotForUserAddress ()
#1  0x80e40ad in free ()
#2  0x806b508 in _efree (ptr=0x46ad3fec, filename=0x80e97d7 "php3_hash.c", 
    lineno=677) at alloc.c:173
#3  0x8065e58 in _php3_hash_destroy (ht=0x4592ffcc) at php3_hash.c:677
#4  0x809e6cf in phpparse () at control_structures_inline.h:956
#5  0x8064c6c in php3_parse (yyin=0x40addf98) at main.c:1563
#6  0x8064ed0 in apache_php3_module_main (r=0x40a8c028, fd=21, 
    display_source_mode=0, preprocessed=0) at main.c:1934
#7  0x806220a in send_php3 (r=0x40a8c028, display_source_mode=0, 
    preprocessed=0, 
    filename=0x40a8cbb0 "/home/zeev/webmail/htdocs/curr/message.php3")
    at mod_php3.c:245
#8  0x806226e in send_parsed_php3 (r=0x40a8c028) at mod_php3.c:261
#9  0x80a881f in ap_invoke_handler (r=0x40a8c028) at http_config.c:508
#10 0x80bb8a9 in process_request_internal (r=0x40a8c028) at http_request.c:1214
#11 0x80bb908 in ap_process_request (r=0x40a8c028) at http_request.c:1230
#12 0x80b3175 in child_main (child_num_arg=2) at http_main.c:4035
#13 0x80b33ac in make_child (s=0x40173028, slot=2, now=936296647)
    at http_main.c:4194
#14 0x80b345b in startup_children (number_to_start=3) at http_main.c:4221
#15 0x80b3a48 in standalone_main (argc=1, argv=0xbffffd6c) at http_main.c:4509
#16 0x80b429b in main (argc=1, argv=0xbffffd6c) at http_main.c:4830
(gdb)