我使用的是Cloudera5.9版本。我尝试了一个简单的select count（*）from table query from hive cli。这份工作永远不会有结果。根据日志，map任务正在100%完成，但是reducer任务甚至还没有开始。

Hadoop job information for Stage-1: number of mappers: 1; number of reducers: 1
2018-06-22 05:56:03,019 Stage-1 map = 0%,  reduce = 0%
2018-06-22 05:56:22,789 Stage-1 map = 16%,  reduce = 0%, Cumulative CPU 11.67 sec
2018-06-22 05:56:41,472 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 31.45 sec
2018-06-22 05:57:41,547 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 31.45 sec
2018-06-22 05:58:42,532 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 31.45 sec
2018-06-22 05:59:43,423 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 31.45 sec
2018-06-22 06:00:44,304 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 31.45 sec
2018-06-22 06:01:45,161 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 31.45 sec
2018-06-22 06:02:45,938 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 31.45 sec
2018-06-22 06:03:46,749 Stage-1 map = 100%,  reduce = 0%, Cumulative CPU 31.45 sec

我试着跑了几个小时，但在减少任务方面仍然没有进展。我查了日志。日志中没有可用信息。
有人能帮我理解在这种情况下会发生什么吗。
提前谢谢。