Pathos multiprocessing pool hangs

Question

I'm trying to use multiprocessing inside docker container. However, I'm facing two issues. (I'm using python 2.7)

1. Creating ProcessingPool()/Pool() (I tried both) takes abnormally long time to create. Maybe over a minute or two.
2. After it processes the function, it hangs.

I basically trying to run a very simple case inside my container. Here's what I have..

import pathos.multiprocessing import ProcessingPool
import multiprocessing

class MultiprocessClassExample():
    .
    .
    .
    def worker(self, number):
        return "Printing number %s" %(number)
    .
    .
    def generateNumber(self):
        PROCESSES = multiprocessing.cpu_count() - 1
        NUMBER = ['One', 'Two', 'Three', 'Four', 'Five']

        result = ProcessingPool(PROCESSES).map(self.worker, NUMBER)
        print("Finished processing.")
        print(result)

and I call using the following code.

    MultiprocessClassExample().generateNumber()

Now, this seems fairly straight forward enough. I ran this on a jupyter notebook and it ran without an issue. I also tried running python inside my docker container, and tried running the above code inside, and it went fine. So I'm assuming it has to do with the complete code that I have. Obviously I didn't write out all the code, but that's the main section of the code I'm trying to handle right now.
I would expect the above code to work as well. However, first thing I notice is that when I call ProcessingPool(), it takes a long time. I tried regular multiprocessing.Pool() before, and had the same effect. Whereas, in the notebook, it ran very quick and smoothly.
After waiting several minutes, it prints :

Printing number One
Printing number Two
Printing number Three
Printing number Four
Printing number Five

and that's it. It never prints out Finished processing. and it just hangs there. But when the print statements appear, I notice that several debug message appear at the same time. It says

[CRITICAL] WORKER TIMEOUT
[WARNING] Worker graceful timeout
[INFO] Worker exiting
[INFO] Booting worker with pid:

Any suggestions would be greatly appreciated.