bug in glib2/gtk2 reactor

New submission from tdelaet <[email protected]>:

In attach you find a test file. In the test, I execute an external command ('/bin/echo test') using twisted.internet.utils.getProcessOutput(). 

If you execute the file with the standard reactor, everything works fine. However, if you comment out the first two lines (they enable the glib2 reactor) and test it again, CPU usage goes to 100% and stays at that level.

Some observations:
 - When I use a  deferred without external process involved (I tested this with callLater), everything works fine.
 - The server does not go to 100% cpu usage on startup, only when the external processes ended.


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Type     : defect
Component: core
Keywords : 
Priority : high
Nosy     : 
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http://twistedmatrix.com/trac/ticket/3981