Using pool.map to run multiple functions in Python

user_4529317 0
Viewed 749

I need to run in parallel multiple functions. I tried this

from multiprocessing import Pool

def smap(f, *args):
    return f(*args)

def somma(*args):
    a=args[0]
    b=args[1]
    return a+b

def prodotto(*args):
    a=args[0]
    b=args[1]
    return a*b

pool = Pool(processes=2)
a=2
b=4
res=pool.map(smap, [(somma,a,b),(prodotto,a,b)])
print(res)

with the following error:

TypeError: 'tuple' object is not callable

What's wrong?

multiprocessing python
3 Answers

You are passing the entire tuple as the first argument f to function smap, which is not a function as you intended. You can change smap to:

def smap(f_args):
    f, *args = f_args
    return f(*args)

This will correctly accept only one argument from Pool.map and split f and args inside the call.

user_140357280

You are expecting the pool.map internals to do the unpacking in smap for you but this is something which the logic cannot handle. You need to explicitely do it yourself.

def smap(params): 
    function, *args = params 

    return function(*args)
user_17944970
user_74300680
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