Run parallel tasks in Python

ParallelBatch.py

# ParallelBatch.py
#
#  Created by Mads Ynddal on 15/07/15.
#  2015 Printix.net
#

from multiprocessing.pool import ThreadPool

class batch:
    processes = 4
    pool = ThreadPool(processes = processes)
    tasks = []
    running = []
    results = []

    def add(self, task):
        self.tasks.append(task)

    def addList(self, taskList):
        for t in taskList:
            self.tasks.append(t)

    def start(self):
        for t in self.tasks:
            r = self.pool.apply_async(t)
            self.running.append(r)

        for r in self.running:
            self.results.append(r.get())


if __name__ == "__main__":
    b = batch()
    b.add(lambda: 2+2)
    b.add(lambda: 3+2)
    b.add(lambda: 4+2)
    b.add(lambda: 5+2)
    b.start()
    print b.results