Using Multiprocessing module for updating Tkinter GUI

You missed out an important part, you should protect your calls with a __main__ trap:

if __name__ == '__main__':     q = Queue.Queue()    # Create a thread and run GUI & QueueHadnler in it    t1 = multiprocessing.Process(target=GenerateData,args=(q,))    t2 = multiprocessing.Process(target=QueueHandler,args=(q,))    ....

Note that the Queue is passed as a parameter rather than using a global.

Edit: just spotted another issue, you should be using Queue from the multiprocessing module, not from Queue:

from multiprocessing import Queue

# Test Code for Tkinter with threadsimport Tkinter as Tkimport multiprocessingfrom Queue import Empty, Fullimport timeclass GuiApp(object):   def __init__(self,q):      self.root = Tk.Tk()      self.root.geometry('300x100')      self.text_wid = Tk.Text(self.root,height=100,width=100)      self.text_wid.pack(expand=1,fill=Tk.BOTH)      self.root.after(100,self.CheckQueuePoll,q)   def CheckQueuePoll(self,c_queue):      try:         str = c_queue.get(0)         self.text_wid.insert('end',str)      except Empty:         pass      finally:         self.root.after(100, self.CheckQueuePoll, c_queue)# Data Generator which will generate Datadef GenerateData(q):   for i in range(10):      print "Generating Some Data, Iteration %s" %(i)      time.sleep(2)      q.put("Some Data from iteration %s \n" %(i))if __name__ == '__main__':# Queue which will be used for storing Data   q = multiprocessing.Queue()   q.cancel_join_thread() # or else thread that puts data will not term   gui = GuiApp(q)   t1 = multiprocessing.Process(target=GenerateData,args=(q,))   t1.start()   gui.root.mainloop()   t1.join()   t2.join()