I have an example code that works fine on Python 2.6.3, but when run in
Python 3.1.1 - after a very short period of time, will go wrong.

Summary:

We have a queue, and when the queue has something in it (a list), we
start a thread to deal with that entry.

The thread then runs a Process for every entry in the list we popped off
the queue. The Process target takes a Pipe, and it sends "True" back
down the pipe, and then exits. However, this Process never goes defunct,
and thus the Thread that started the Process never reaps it. When doing
a truss on the Process, it sits there in:

lwp_park(0x00000000, 0)         (sleeping...)