[Twisted-Python] "_wait" is blowing up?!

[Jean-Paul Calderone]

On Thu, 28 Aug 2008 11:52:02 -0700, Brian Granger <ellisonbg.net at gmail.com> wrote:
>> Is your code available somewhere?
>
>yes, the code is the IPython mainline, on launchpad:
>
>$ bzr branch lp:ipython
>
>Then, simply
>
>$ trial IPython
>
>Will show the problem.  You will also need foolcap to run the test suite.
>
>> Do you reliably see this error eventually if you use trial --until- failure?
>
>It shows up as an Error rather than a Failure.  But yes, it still shows up.
>
>> Exactly what version of Twisted are you using?
>
>Latest stable.
>
>> What reactor do you typically run your tests under?
>
>Default on all platforms.
>
>> Not sure that I'd be able to tell you what's going on even with an answer to
>> all of these questions, but they'd be a start :).
>
>Thanks, I know this type of thing is tough to debug.  Any clever
>tricks I could use to track it down?

You can try running with trial --debug (possibly also --nopm).  This will
cause Deferred debugging to be enabled, which will cause the call site of
each Deferred's creation to be saved.  Then you can inspect this to learn
which Deferred is being called back multiple times.  Once you learn this,
further debugging approaches may become apparent (like looking at all the
call sites which can call back a Deferred created there, and figuring out
how more than one of them can be executed).

Jean-Paul