[mailto:firstname.lastname@example.org] On Behalf Of Richard
Sent: December 1, 2006 12:56 PM
To: Fedora Directory server developer discussion.
Subject: [Fedora-directory-devel] Please review: Bug 218076: Server autoconf
build crashes when stopped/started very quickly
Bug(s) fixed: 218076
Bug Description: Server autoconf build crashes when stopped/started very
quickly Reviewed by: ???
Files: see diff
Fix Description: The problem was that 3 of the database threads were being
started and stopped before the 4th had a chance to start. So the thread
count would start at 3 and drop to 0, and the dblayer_pre_close code would
think everything was fine. The 4th thread is the checkpoint thread which
was doing a db_checkpoint operation before incrementing the thread count.
For some reason, on x86_64 with the system provided libdb-4.2, the
checkpoint operation was taking longer than it usually does with our locally
built libdb-4.2, so this allowed the other 3 threads to stop and start
before the checkpoint thread had a chance to increment the thread count.
The solution is to make sure the incrementing of the thread count occurs as
early as possible in the thread function, before any executable code that
might take any time. This should ensure that all of the threads start up
and increment the thread count before the shutdown occurs.
The second part of the solution is that, according to wtc, the NSPR
maintainer, the PR_Atomic functions should not be used as a semaphore like
this. So, the code was rewritten to use locks and condition variables. The
code is not performance critical, so adding locking should not have any
impact on performance. In addition, the new code is much cleaner, more
correct, and more obvious about what it's doing.
Platforms tested: RHEL4 x86_64
Flag Day: no
Doc impact: no
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