> Richard, do you still want to push this forward? Otherwise I'd like to 
> finalize the patch (in the other sense ;-).

I started to worry a bit about daemon threads.  I think they can still run while atexit functions are being run.*  So if a daemon thread creates an atexit finalizer during shutdown it may never be run.

I am not sure how much to worry about this potential race.  Maybe a lock could be used to cause any daemon threads which try to create finalizers to block.

* Is it necessary/desirable to allow daemon threads to run during shutdown.  Maybe blocking thread switching at shutdown could cause deadlocks?