import multiprocessing as mp

from time import sleep


class Cluster:

    def __init__(self, shards, function):
        self._workers = [mp.Process(target=self._run_single,
                                    args=(function, shard))
                         for shard in range(shards)]

    def run(self):
        for worker in self._workers:
            worker.start()
        return self

    def join(self):
        for worker in self._workers:
            worker.join()

    def _run_single(self, function, shard):
        function(shard)


def function(shard):
    for i in range(3):
        print(shard, i)
        sleep(0.1)


if __name__ == '__main__':
    mp.set_start_method('forkserver')
    Cluster(2, function).run().join()