[Pkg-utopia-maintainers] Bug#426412: Bug#426412: Bug#426412: python-dbus: system_bus.remove_signal_receiver() freezes

[Simon McVittie]

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On Mon, 28 May 2007 at 20:22:21 +0100, Tony Houghton wrote:
> In <20070528174346.GA30779 at celebrin.pseudorandom.co.uk>, you wrote:
> 
> > remove_signal_receiver() takes and releases a lock (which protects the
> > signal-match tree from concurrent modification when dbus-python is used
> > multi-threaded). I'll check other places where this lock is used -
> > there's probably some code path where it's not being released properly.
> 
> FWIW after I read this I thought perhaps it's a reentrancy problem,
> caused by the application trying to call remove_signal_receiver() from a
> signal receiver. So I made DevTray defer the calls with
> gobject.idle_add() but it still froze. So I was on the wrong track :-(.

No, it's a different sort of reentrancy problem - in a proxy that tracks
name-owner changes, remove_signal_receiver() can trigger a recursive call
to itself (internally, a match on NameOwnerChanged is removed too) which
attempts to re-take the lock.

I've sent a patch for review upstream; there should be a 0.81.1 in a day or
so.

	Simon
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