Simple Threading Example Doesn't Work (2.5.1)

[Seun Osewa]

Hello,

I've tried to run several threading examples in Python 2.5.1 (with
Stackless) For example:

    import threading

    theVar = 1

    class MyThread ( threading.Thread ):

       def run ( self ):

          global theVar
          print 'This is thread ' + str ( theVar ) + ' speaking.'
          print 'Hello and good bye.'
          theVar = theVar + 1

    for x in xrange ( 20 ):
       MyThread().start()

It doesn't work.  It says there's an error in Queue.py in:
      self.mutex=threading.Lock()
AttributeError: 'module' object has no attribute Lock

The funny thing is that when I use the -O switch, it seems to work.
I'm baffled by this.  What do you think is happening?

Thanks.