Task manager lockup during shutdown
named locked up during shutdown in the
rndc system test (though I believe the problem is a generic one).
Looking at the core dump, it appears that by the time
isc_thread_join() is called in a loop inside
isc_taskmgr_destroy(), at least the first worker thread (
i == 0) has not yet woken up and is still waiting for the
work_available condition variable to be signalled (which
wake_all_queues() should have taken care of). Both the
ready_priority_tasks lists for
manager->queues are empty.