import threading

def getdocs():
    while True:
        yield None

class B(object):
   def doit(self):
       self.docIter = getdocs()
       self.docIter.next()
       print 'exiting generator'

class A(object):
   def run(self):
       while True:
           self.func()

   def func(self):
       b = B()
       thread = threading.Thread(target=b.doit)
       thread.start()
       try:
           raise Exception
       except Exception:
           thread.join()
           print 'joined thread'

if __name__ == '__main__':
   a = A()
   a.run()