httpd/modperl children futex issue

mhearse has asked for the wisdom of the Perl Monks concerning the following question:

I have a modperl issue that I need help with. I'm running httpd2.2.3. Some modperl children aren't dying when the script finishes. After a given time period, all available memory/swap is uses by httpd/modperl children which won't die. strace reviews a wait on futex. I'm just looking for ideas. Right now I just restart httpd every so often. Any input is appreciated. Here is a stack trace:

#0  0x00002aaaac850618 in __lll_mutex_lock_wait () from /lib64/libc.so
+.6
#1  0x00002aaaac7e9ced in _L_lock_14439 () from /lib64/libc.so.6
#2  0x00002aaaac7e8d7b in realloc () from /lib64/libc.so.6
#3  0x00002aaab78c0816 in PyList_Fini () from /usr/lib64/libpython2.4.
+so.1.0
#4  0x00002aaab78c0981 in PyList_Fini () from /usr/lib64/libpython2.4.
+so.1.0
#5  0x00002aaab791c806 in PyMarshal_ReadShortFromFile ()
#6  0x00002aaab791c3d5 in PyMarshal_ReadShortFromFile ()
#7  0x00002aaab791c4f8 in PyMarshal_ReadShortFromFile ()
#8  0x00002aaab791c3d5 in PyMarshal_ReadShortFromFile ()
#9  0x00002aaab791c4ed in PyMarshal_ReadShortFromFile ()
#10 0x00002aaab791cc71 in PyMarshal_ReadObjectFromString ()
#11 0x00002aaab791e435 in PyMarshal_ReadLastObjectFromFile ()
#12 0x00002aaab7917819 in _PyImport_IsScript ()
#13 0x00002aaab7919655 in PyImport_ImportFrozenModule ()
#14 0x00002aaab791a3dd in PyImport_ReloadModule ()
#15 0x00002aaab791a85c in PyImport_ReloadModule ()
#16 0x00002aaab791aa67 in PyImport_ImportModuleEx ()
#17 0x00002aaab78fb5d3 in _PyBuiltin_Init ()
#18 0x00002aaab78a4f90 in PyObject_Call () from /usr/lib64/libpython2.
+4.so.1.0
#19 0x00002aaab78a5be3 in PyObject_CallFunction ()
#20 0x00002aaab791ae78 in PyImport_Import ()
#21 0x00002aaab791b025 in PyImport_ImportModule ()
#22 0x00002aaab7922a10 in PyRun_AnyFile () from /usr/lib64/libpython2.
+4.so.1.0
#23 0x00002aaab7922bb3 in Py_NewInterpreter ()
#24 0x00002aaab764cbc5 in init_apache () from /etc/httpd/modules/mod_p
+ython.so
#25 0x00002aaab764d11d in init_apache () from /etc/httpd/modules/mod_p
+ython.so
#26 0x00002aaaac1454fd in apr_pool_cleanup_run () from /usr/lib64/liba
+pr-1.so.0
#27 0x00002aaaac145b0d in apr_pool_destroy () from /usr/lib64/libapr-1
+.so.0
#28 0x000055555558eeae in ap_graceful_stop_signalled () from /proc/292
+06/exe
#29 0x000055555558eedb in ap_graceful_stop_signalled () from /proc/292
+06/exe
#30 <signal handler called>
#31 0x00002aaaac80b5f9 in fork () from /lib64/libc.so.6
#32 0x00002aaab546eacd in Perl_pp_system ()
#33 0x00002aaab54300ae in Perl_runops_standard ()
#34 0x00002aaab53dd580 in Perl_call_sv ()
#35 0x00002aaab5185b97 in modperl_callback ()
#36 0x00002aaab51862af in modperl_callback_run_handlers ()
#37 0x00002aaab51867ef in modperl_callback_per_dir ()
#38 0x00002aaab51808f0 in modperl_response_init ()
#39 0x00002aaab5180ab3 in modperl_response_handler_cgi ()
#40 0x000055555557d84a in ap_run_handler () from /proc/29206/exe
#41 0x0000555555580cc2 in ap_invoke_handler () from /proc/29206/exe
#42 0x000055555558b678 in ap_process_request () from /proc/29206/exe
#43 0x0000555555588900 in ap_register_input_filter () from /proc/29206
+/exe
#44 0x0000555555584a92 in ap_run_process_connection () from /proc/2920
+6/exe
#45 0x000055555558f27b in ap_graceful_stop_signalled () from /proc/292
+06/exe
#46 0x000055555558f50a in ap_graceful_stop_signalled () from /proc/292
+06/exe
#47 0x000055555558fd7b in ap_mpm_run () from /proc/29206/exe
#48 0x000055555556ade4 in main () from /proc/29206/exe
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Re: httpd/modperl children futex issue by perrin (Chancellor) on Jan 25, 2008 at 00:07 UTC
The best place to ask is the mod_perl mailing list. However, it's not clear to me what you're saying. With mod_perl, processes are not supposed to die after they finish a request. They stay around to handle more requests. You should set your MaxClients low enough to avoid forking more processes than you have room for on your machine.	[reply]
Re: httpd/modperl children futex issue by almut (Canon) on Jan 24, 2008 at 21:54 UTC
I see lots of Py*s in the critical places... so there's an off chance you're asking in the wrong forum :) — Just a thought.	[reply]