test.py

from multiprocessing import Pool
import os
from test_common import *

class Test:
    def __init__(self):
        self.A = A()
        self.B = B()

    def run(self):
        data_list = list(range(10001, 11984))

        a_list = self.A.run(data_list)
        print("self.A.run end") #1

        new_list = self.B.run(data_list, a_list)
        print("self.B.run end") #2


def main():
    run_module = Test()
    run_module.run()

if __name__ == '__main__':
    main()

---------------------------------------------
test_common.py

import os
import multiprocessing
from multiprocessing import Pool
import io
import datetime
import time

class A:
    def __init__(self):
        pass

    def run(self, data_list):
        a_list = []
        for item in data_list:
            file_path = "{}/{}.aaa".format("/tmp/aaa", item)
            a_list.append(file_path)

        pool_size = 1
        pool = Pool(pool_size)
        pool.map(methodA, a_list)
        print("A#run end") #3
        return a_list


def methodA(file_path):
    if os.path.isfile(file_path):
        return
    # other code

class B:
    def __init__(self):
        pass

    def run(self, data_list, a_list):        
        b_list = []
        for item in data_list:
            b_path = "{}/{}.bbb".format("/tmp/bbb", item)
            b_list.append(b_path)

        pool_size = 1
        pool = Pool(pool_size)
        pool.map(methodB, b_list)
 
        print("B#run end") #4
        return b_list

def methodB(b_path):
    if os.path.isfile(b_path):
        return
    # other code