I’m trying to get to grips with pythons multiprocessing module, specifically the apply_async method of Pool
. I’m trying to call a function with arguments and keyword arguments. If I call the function without kwargs it’s fine but when I try to add in a keyword argument I get:
TypeError: apply_async() got an unexpected keyword argument 'arg2'
Below is the test code that I’m running
#!/usr/bin/env python import multiprocessing from time import sleep def test(arg1, arg2=1, arg3=2): sleep(5) if __name__ == '__main__': pool = multiprocessing.Pool() for t in range(1000): pool.apply_async(test, t, arg2=5) pool.close() pool.join()
How can I call the function so that it accepts keyword arguments?
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Answer
Pass the keyword args in a dictionary (and the positional arguments in a tuple):
pool.apply_async(test, (t,), dict(arg2=5))