'Start the pool and workers
:return: The pool instance'

def start_workers(self):

    with self._start_lock:
        if (self._pool is None):
            self._processes = manager.dict()
            log_queue = om.manager.get_in_queue()
            self._pool = ProcessPool(self.MAX_WORKERS, maxtasksperchild=20, initializer=init_worker, initargs=(log_queue,))
    return self._pool
