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Re: (ITS#6856) OpenLDAP 2.4.23 / db 4.7.25 lockup 100% CPU

requate@univention.de wrote:
> Full_Name: Arvid Requate
> Version: 2.4.23
> OS: Debian Lenny
> URL: http://apt.univention.de/download/temp/openldap/trace_openldap_2.4.23_db_4.7.25.tar.gz
> Submission from: (NULL) (
> With OpenLDAP 2.4.23 and bdb 4.7.25 we seem to hit something like a race
> condition that can be triggered by concurrent ldapdelete and search_s
> operations.
> Though a bit simmilar, this condition does no quite match the details of
> ITS#5707. The URL provides a tar archive containing three gdb traces and
> corresponding slapd log output (loglevel: trace args stats) of three cases of
> lockup, where slapd hangs consuming 100% of CPU after a couple of modifications
> with the shell script contained in the tar archive and remains unresponsive
> until restartet.The number of successful operations varies between the test
> runs.
> Berkeley DB 4.7.25 (May 15, 2008) was built with Oracle patches for Bugs #16415
> and #16541 and configure options "--enable-posixmutexes
> --with-mutex=POSIX/pthreads".
> The test machine is a single processor/single core 686 VM running Linux 2.6.32
> 686 bigmem. The concurrent searches are performed by a separate process that
> gets informed about ldap modifications (via file) by an slapd overlay module
> called 'translog'. To me the traces do not seem to indicate a problem in the
> overlay code (i.e. there is no reference to the on_response function
> "translog_response" in the traces).
> Maybe there is some obvious point here we are missing? More debug details can be
> provided if necessary.

Try again using 2.4.24. There was a bug with back-bdb delete fixed recently 
(ITS#6577) so the relevant code has changed since .23.

Also try a newer BerkeleyDB. We've had other deadlocks with 4.7 that no longer 
occur in 4.8.

   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/