100% CPU utilization in Zope after LDAP connection timeout

Matthew X. Economou xenophon at irtnog.org
Thu Mar 17 13:51:30 CET 2005


I installed python-ldap 2.0.6 on Python 2.4 and using OpenLDAP 2.2.23,
all of which came from the FreeBSD ports tree.  According to ldd(1),
python-ldap's helper library links to the reentrant versions of the
OpenLDAP client libraries:

        libldap_r-2.2.so.7 => /usr/local/lib/libldap_r-2.2.so.7
        liblber-2.2.so.7 => /usr/local/lib/liblber-2.2.so.7
        libssl.so.3 => /usr/lib/libssl.so.3
        libcrypto.so.3 => /lib/libcrypto.so.3

I traced the Zope process with ktrace(8).  There are a number of calls
to poll(2) and the SIGPROF signal handler (which resets itself,
apparently, as I see follow-up calls to gettimeofday(2) and
sigprocmask(2)).  These calls repeat.  I believe SIGPROF is used by the
threading implementation.

I attached to the Zope instance with GDB.  While it doesn't list any
threads (command "info threads"), GDB gives me the following backtrace:

(gdb) bt
#0  0x00000001601bd320 in _get_curthread () from /usr/lib/libc_r.so.5
#1  0x00000001601c1be4 in _thread_leave_cancellation_point () from
#2  0x00000001601b70e8 in select () from /usr/lib/libc_r.so.5
#3  0x0000000160ca4644 in ldap_int_select () from
#4  0x0000000160c8c9a4 in wait4msg () from
#5  0x0000000160c8c440 in ldap_result () from
#6  0x0000000160c5ce50 in l_ldap_result2 () from
#7  0x00000001200cf9ac in PyCFunction_Call ()
#8  0x00000001200186f4 in PyObject_Call ()
#9  0x0000000120080228 in PyEval_GetFuncDesc ()
#10 0x000000012007c7a8 in PyEval_EvalCode ()
#11 0x000000012007dcb8 in PyEval_EvalCodeEx ()

> Could you please try to reproduce this problem without Zope? Maybe
> some small multi-threaded client app sending similar LDAP requests
> to the server?

I wish I knew enough Python to write a few test cases of my own.  I will

Best wishes,

"The challenge of a moral life is to do nothing that requires
forgiveness."  - Roger Ebert in his review of _The Woodsman_

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