// ��Ҫ�Ƿ�ֹ ��bolt�У����ҵ������bug����ijһ���������ǵ���ack��fail���ͻᵼ������mapԽ��Խ��ֱ���ڴ治����
this.tuple_start_times = new TimeCacheMap<Tuple, Long>(
message_timeout_secs);
IOutputCollector output_collector = new BoltCollector(
message_timeout_secs, _report_error, _send_fn, _transfer_fn,
_topology_context, task_id, tuple_start_times, _task_stats);
LOG.info("Preparing bolt " + component_id + ":" + task_id);
bolt.prepare(storm_conf, _user_context, new OutputCollector(
output_collector));