Python GUI is not responding while thread is executing

Question

I have Python GUI, and in one for-loop I call function from some dll which returns values for populating tableWidget row by row. All this works fine, except I can't scroll table while it's still populating (while dll function calculating things - 7-8secs for each row) so I tried work with threads like this:

q = Queue.Queue()
for i in (0, numberOfRows):
    threading.Thread(target=self.callFunctionFromDLL, args=(arg1,arg2, q)).start()
    result = q.get()
    ... do something with "result" and populate table row....


def callFunctionFromDLL(self, arg1, arg2, q):
    result = self.dll.functionFromDLL(arg1, arg2)
    q.put(result)

but still GUI is not responding until result is passed from q.get (functionFromDLL works 7-8 secs, and than for a moment while GUI populating row I can scroll table). I didn't really worked with threads before, so any suggestion or example how to do this would be appreciated.

I've also tried this way, same thing, gui still not responding while functionFromDLL works:

for i in (0, numberOfRows):
    t = threading.Thread(target=self.callFunctionFromDLL, args=(arg1,arg2))
    t.start()
    t.join()
    result = self.result
    ... do something with "result" and populate table row....


def callFunctionFromDLL(self, arg1, arg2):
    self.result = self.dll.functionFromDLL(arg1, arg2)

Noctis Skytower · Accepted Answer · 2012-11-27 15:10:56Z

2

If you are using the tkinter module, you might be able to get some help from how Directory Pruner 4 is implemented. To get around the fact that most GUI libraries do not play well with threads, the recipe utilizes some custom modules listed below the code. The modules affinity, threadbox, and safetkinter provide a thread-safe wrapping of the GUI library the program uses.

answered Nov 27, 2012 at 15:10

Noctis Skytower

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2 Comments

Noctis Skytower Over a year ago

@Aleksandar: You may be able to create your own safeGUI module by following the example of safetkinter. What library do you use to generate your interface?

Aleksandar Over a year ago

I've created it using Qt Designer

Mike DeSimone · Accepted Answer · 2012-11-26 14:24:32Z

0

CPython (what you probably have) has a Global Interpreter Lock in it that defeats a lot of multithreading. This is a known problem that has proven difficult to solve. (Look up "Python GIL" for more info.) Some other implementations, such as Jython, don't have this problem.

answered Nov 26, 2012 at 14:24

Mike DeSimone

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1 Comment

Aleksandar Over a year ago

Tnx for your answer, but is there any other way of doing this? It would be ugly if I leave my GUI to go not responding for few seconds every time functionFromDLL is called

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