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From YanTangZhai <...@git.apache.org>
Subject [GitHub] spark pull request: [SPARK-3545] Put HadoopRDD.getPartitions forwa...
Date Tue, 16 Sep 2014 13:26:27 GMT
GitHub user YanTangZhai opened a pull request:

    https://github.com/apache/spark/pull/2409

    [SPARK-3545] Put HadoopRDD.getPartitions forward and put TaskScheduler.start back to reduce
DAGScheduler.JobSubmitted processing time and shorten cluster resources occupation period

    We have two problems:
    (1) HadoopRDD.getPartitions is lazyied to process in DAGScheduler.JobSubmitted. If inputdir
is large, getPartitions may spend much time.
    For example, in our cluster, it needs from 0.029s to 766.699s. If one JobSubmitted event
is processing, others should wait. Thus, we
    want to put HadoopRDD.getPartitions forward to reduce DAGScheduler.JobSubmitted processing
time. Then other JobSubmitted event don't
    need to wait much time. HadoopRDD object could get its partitons when it is instantiated.
    (2) When SparkContext object is instantiated, TaskScheduler is started and some resources
are allocated from cluster. However, these
    resources may be not used for the moment. For example, DAGScheduler.JobSubmitted is processing
and so on. These resources are wasted in
    this period. Thus, we want to put TaskScheduler.start back to shorten cluster resources
occupation period specially for busy cluster.
    TaskScheduler could be started just before running stages.
    We could analyse and compare the execution time before and after optimization.
    TaskScheduler.start execution time: [time1__]
    DAGScheduler.JobSubmitted (excluding HadoopRDD.getPartitions or TaskScheduler.start) execution
time: [time2_]
    HadoopRDD.getPartitions execution time: [time3___]
    Stages execution time: [time4_____]
    (1) The app has only one job
    (a)
    The execution time of the job before optimization is [time1__][time2_][time3___][time4_____].
    The execution time of the job after optimization is....[time3___][time2_][time1__][time4_____].
    (b)
    The cluster resources occupation period before optimization is [time2_][time3___][time4_____].
    The cluster resources occupation period after optimization is....[time4_____].
    In summary, if the app has only one job, the total execution time is same before and after
optimization while the cluster resources
    occupation period after optimization is less than before.
    (2) The app has 4 jobs
    (a) Before optimization,
    job1 execution time is [time2_][time3___][time4_____],
    job2 execution time is [time2__________][time3___][time4_____],
    job3 execution time is................................[time2____][time3___][time4_____],
    job4 execution time is................................[time2______________][time3___][time4_____].
    After optimization, 
    job1 execution time is [time3___][time2_][time1__][time4_____],
    job2 execution time is [time3___][time2__________][time4_____],
    job3 execution time is................................[time3___][time2_][time4_____],
    job4 execution time is................................[time3___][time2__][time4_____].
    In summary, if the app has multiple jobs, average execution time after optimization is
less than before and the cluster resources
    occupation period after optimization is less than before.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/YanTangZhai/spark SPARK-3545

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/spark/pull/2409.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #2409
    
----
commit cdef539abc5d2d42d4661373939bdd52ca8ee8e6
Author: YanTangZhai <hakeemzhai@tencent.com>
Date:   2014-08-06T13:07:08Z

    Merge pull request #1 from apache/master
    
    update

commit cbcba66ad77b96720e58f9d893e87ae5f13b2a95
Author: YanTangZhai <hakeemzhai@tencent.com>
Date:   2014-08-20T13:14:08Z

    Merge pull request #3 from apache/master
    
    Update

commit 8a0010691b669495b4c327cf83124cabb7da1405
Author: YanTangZhai <hakeemzhai@tencent.com>
Date:   2014-09-12T06:54:58Z

    Merge pull request #6 from apache/master
    
    Update

commit 03b62b043ab7fd39300677df61c3d93bb9beb9e3
Author: YanTangZhai <hakeemzhai@tencent.com>
Date:   2014-09-16T12:03:22Z

    Merge pull request #7 from apache/master
    
    Update

commit b88df438033eecbdbe8cad37b2bd4ad3620de6e2
Author: yantangzhai <tyz0303@163.com>
Date:   2014-09-16T13:22:12Z

    [SPARK-3545] Put HadoopRDD.getPartitions forward and put TaskScheduler.start back to reduce
DAGScheduler.JobSubmitted processing time and shorten cluster resources occupation period

----


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