hive.exec.parallel参数控制在同一个sql中的不同的job是否可以同时运行,默认为false.
下面是对于该参数的测试过程:
测试sql:
select r1.a
from (select t.a from sunwg_10 t join sunwg_10000000 s on t.a=s.b) r1 join (select s.b from sunwg_100000 t join sunwg_10 s on t.a=s.b) r2 on (r1.a=r2.b);
1,
Set hive.exec.parallel=false;
当参数为false的时候,三个job是顺序的执行
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hive> set hive.exec.parallel=false;
hive> select r1.a
> from (select t.a from sunwg_10 t join sunwg_10000000 s on t.a=s.b) r1 join (select s.b from sunwg_100000 t join sunwg_10 s on t.a=s.b) r2 on (r1.a=r2.b);
Total MapReduce jobs = 3 Launching Job 1 out of 3
Number of reduce tasks not specified. Estimated from input data size: 1
In order to change the average load for a reducer (in bytes):
set hive.exec.reducers.bytes.per.reducer=<number>
In order to limit the maximum number of reducers:
set hive.exec.reducers.max=<number>
In order to set a constant number of reducers:
set mapred.reduce.tasks=<number>
Cannot run job locally: Input Size (= 397778060) is larger than hive.exec.mode.local.auto.inputbytes.max (= -1)
Starting Job = job_201208241319_2001905, Tracking URL = http://hdpjt:50030/jobdetails.jsp?jobid=job_201208241319_2001905 Kill Command = /dhwdata/hadoop/bin/../bin/hadoop job -Dmapred.job.tracker=hdpjt:9001 -kill job_201208241319_2001905 Hadoop job information for Stage-1: number of mappers: 7; number of reducers: 1
2012-09-07 17:55:40,854 Stage-1 map = 0%, reduce = 0% 2012-09-07 17:55:55,663 Stage-1 map = 14%, reduce = 0% 2012-09-07 17:56:00,506 Stage-1 map = 56%, reduce = 0% 2012-09-07 17:56:10,254 Stage-1 map = 100%, reduce = 0% 2012-09-07 17:56:19,871 Stage-1 map = 100%, reduce = 29% 2012-09-07 17:56:30,000 Stage-1 map = 100%, reduce = 75% 2012-09-07 17:56:34,799 Stage-1 map = 100%, reduce = 100% Ended Job = job_201208241319_2001905 Launching Job 2 out of 3
Number of reduce tasks not specified. Estimated from input data size: 1
In order to change the average load for a reducer (in bytes):
set hive.exec.reducers.bytes.per.reducer=<number>
In order to limit the maximum number of reducers:
set hive.exec.reducers.max=<number>
In order to set a constant number of reducers:
set mapred.reduce.tasks=<number>
Cannot run job locally: Input Size (= 3578060) is larger than hive.exec.mode.local.auto.inputbytes.max (= -1)
Starting Job = job_201208241319_2002054, Tracking URL = http://hdpjt:50030/jobdetails.jsp?jobid=job_201208241319_2002054 Kill Command = /dhwdata/hadoop/bin/../bin/hadoop job -Dmapred.job.tracker=hdpjt:9001 -kill job_201208241319_2002054 Hadoop job information for Stage-4: number of mappers: 2; number of reducers: 1
2012-09-07 17:56:43,343 Stage-4 map = 0%, reduce = 0% 2012-09-07 17:56:48,124 Stage-4 map = 50%, reduce = 0% 2012-09-07 17:56:55,816 Stage-4 map = 100%, reduce = 0% Ended Job = job_201208241319_2002054 Launching Job 3 out of 3
Number of reduce tasks not specified. Estimated from input data size: 1
In order to change the average load for a reducer (in bytes):
set hive.exec.reducers.bytes.per.reducer=<number>
In order to limit the maximum number of reducers:
set hive.exec.reducers.max=<number>
In order to set a constant number of reducers:
set mapred.reduce.tasks=<number>
Cannot run job locally: Input Size (= 596) is larger than hive.exec.mode.local.auto.inputbytes.max (= -1)
Starting Job = job_201208241319_2002120, Tracking URL = http://hdpjt:50030/jobdetails.jsp?jobid=job_201208241319_2002120 Kill Command = /dhwdata/hadoop/bin/../bin/hadoop job -Dmapred.job.tracker=hdpjt:9001 -kill job_201208241319_2002120 Hadoop job information for Stage-2: number of mappers: 2; number of reducers: 1
2012-09-07 17:57:12,641 Stage-2 map = 0%, reduce = 0% 2012-09-07 17:57:19,571 Stage-2 map = 50%, reduce = 0% 2012-09-07 17:57:25,199 Stage-2 map = 100%, reduce = 0% 2012-09-07 17:57:29,210 Stage-2 map = 100%, reduce = 100% Ended Job = job_201208241319_2002120 OK abcdefghijk_0 abcdefghijk_1 abcdefghijk_2 abcdefghijk_3 abcdefghijk_4 abcdefghijk_5 abcdefghijk_6 abcdefghijk_7 abcdefghijk_8 abcdefghijk_9 Time taken: 135.944 seconds
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2,
但是可以看出来其实两个子查询中的sql并无关系,可以并行的跑
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hive> set hive.exec.parallel=true;
hive> select r1.a
> from (select t.a from sunwg_10 t join sunwg_10000000 s on t.a=s.b) r1 join (select s.b from sunwg_100000 t join sunwg_10 s on t.a=s.b) r2 on (r1.a=r2.b);
Total MapReduce jobs = 3 Launching Job 1 out of 3
Launching Job 2 out of 3
Number of reduce tasks not specified. Estimated from input data size: 1
In order to change the average load for a reducer (in bytes):
set hive.exec.reducers.bytes.per.reducer=<number>
In order to limit the maximum number of reducers:
set hive.exec.reducers.max=<number>
In order to set a constant number of reducers:
set mapred.reduce.tasks=<number>
Cannot run job locally: Input Size (= 397778060) is larger than hive.exec.mode.local.auto.inputbytes.max (= -1)
Number of reduce tasks not specified. Estimated from input data size: 1
In order to change the average load for a reducer (in bytes):
set hive.exec.reducers.bytes.per.reducer=<number>
In order to limit the maximum number of reducers:
set hive.exec.reducers.max=<number>
In order to set a constant number of reducers:
set mapred.reduce.tasks=<number>
Cannot run job locally: Input Size (= 3578060) is larger than hive.exec.mode.local.auto.inputbytes.max (= -1)
Starting Job = job_201208241319_2001452, Tracking URL = http://hdpjt:50030/jobdetails.jsp?jobid=job_201208241319_2001452 Kill Command = /dhwdata/hadoop/bin/../bin/hadoop job -Dmapred.job.tracker=hdpjt:9001 -kill job_201208241319_2001452 Starting Job = job_201208241319_2001453, Tracking URL = http://hdpjt:50030/jobdetails.jsp?jobid=job_201208241319_2001453 Kill Command = /dhwdata/hadoop/bin/../bin/hadoop job -Dmapred.job.tracker=hdpjt:9001 -kill job_201208241319_2001453 Hadoop job information for Stage-4: number of mappers: 2; number of reducers: 1
Hadoop job information for Stage-1: number of mappers: 7; number of reducers: 1
2012-09-07 17:52:10,558 Stage-4 map = 0%, reduce = 0% 2012-09-07 17:52:10,588 Stage-1 map = 0%, reduce = 0% 2012-09-07 17:52:22,827 Stage-1 map = 14%, reduce = 0% 2012-09-07 17:52:22,880 Stage-4 map = 100%, reduce = 0% 2012-09-07 17:52:27,678 Stage-1 map = 22%, reduce = 0% 2012-09-07 17:52:28,701 Stage-1 map = 36%, reduce = 0% 2012-09-07 17:52:31,137 Stage-1 map = 93%, reduce = 0% 2012-09-07 17:52:33,551 Stage-1 map = 100%, reduce = 0% 2012-09-07 17:52:36,427 Stage-4 map = 100%, reduce = 100% Ended Job = job_201208241319_2001453 2012-09-07 17:52:42,883 Stage-1 map = 100%, reduce = 33% 2012-09-07 17:52:45,431 Stage-1 map = 100%, reduce = 70% 2012-09-07 17:52:47,526 Stage-1 map = 100%, reduce = 76% 2012-09-07 17:52:51,829 Stage-1 map = 100%, reduce = 84% Ended Job = job_201208241319_2001452 Launching Job 3 out of 3
Number of reduce tasks not specified. Estimated from input data size: 1
In order to change the average load for a reducer (in bytes):
set hive.exec.reducers.bytes.per.reducer=<number>
In order to limit the maximum number of reducers:
set hive.exec.reducers.max=<number>
In order to set a constant number of reducers:
set mapred.reduce.tasks=<number>
Cannot run job locally: Input Size (= 596) is larger than hive.exec.mode.local.auto.inputbytes.max (= -1)
Starting Job = job_201208241319_2001621, Tracking URL = http://hdpjt:50030/jobdetails.jsp?jobid=job_201208241319_2001621 Kill Command = /dhwdata/hadoop/bin/../bin/hadoop job -Dmapred.job.tracker=hdpjt:9001 -kill job_201208241319_2001621 Hadoop job information for Stage-2: number of mappers: 2; number of reducers: 1
2012-09-07 17:53:07,081 Stage-2 map = 0%, reduce = 0% 2012-09-07 17:53:10,351 Stage-2 map = 50%, reduce = 0% 2012-09-07 17:53:11,380 Stage-2 map = 100%, reduce = 0% 2012-09-07 17:53:18,132 Stage-2 map = 100%, reduce = 100% Ended Job = job_201208241319_2001621 OK abcdefghijk_0 abcdefghijk_1 abcdefghijk_2 abcdefghijk_3 abcdefghijk_4 abcdefghijk_5 abcdefghijk_6 abcdefghijk_7 abcdefghijk_8 abcdefghijk_9 Time taken: 108.301 seconds
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总结:
在资源充足的时候hive.exec.parallel会让那些存在并发job的sql运行得更快,但同时消耗更多的资源
可以评估下hive.exec.parallel对我们的刷新任务是否有帮助.
转自 ：http://www.oratea.net/?p=1377
本文转自茄子_2008博客园博客，原文链接：http://www.cnblogs.com/xd502djj/archive/2013/05/08/3067699.html，如需转载请自行联系原作者。