process.py 文件源码

def _process_worker(call_queue, result_queue):
    """Evaluates calls from call_queue and places the results in result_queue.

    This worker is run in a separate process.

    Args:
        call_queue: A multiprocessing.Queue of _CallItems that will be read and
            evaluated by the worker.
        result_queue: A multiprocessing.Queue of _ResultItems that will written
            to by the worker.
        shutdown: A multiprocessing.Event that will be set as a signal to the
            worker that it should exit when call_queue is empty.
    """
    while True:
        call_item = call_queue.get(block=True)
        if call_item is None:
            # Wake up queue management thread
            result_queue.put(None)
            return
        try:
            r = call_item.fn(*call_item.args, **call_item.kwargs)
        except BaseException:
            e = sys.exc_info()[1]
            result_queue.put(_ResultItem(call_item.work_id,
                                         exception=e))
        else:
            result_queue.put(_ResultItem(call_item.work_id,
                                         result=r))