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https://issues.apache.org/jira/browse/HADOOP-4558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12647273#action_12647273
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Amar Kamat commented on HADOOP-4558:
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Note that once a task is assigned, capacity scheduler is not updated to reflect
the change. It waits for a heartbeat to update itself via
{{updateQSIObjects()}}. I feel its better we update the scheduler after the
tasks are assigned so that the scheduler is up to date. This needs benchmarking
and discussion. Following is the use case
- job1 is added
- job1 takes up one slot more than guaranteed
- job2 is added
- ideally the reclaim thread should detect the capacity violation and kill that
one extra task but will not do as the count is stale and one less.
- upon next heartbeat the scheduler will detect that job1 has violated and
hence will start the reclaim process.
> Scheduler fails to reclaim capacity if Jobs are submitted to queue one after
> the other
> --------------------------------------------------------------------------------------
>
> Key: HADOOP-4558
> URL: https://issues.apache.org/jira/browse/HADOOP-4558
> Project: Hadoop Core
> Issue Type: Bug
> Components: contrib/capacity-sched
> Affects Versions: 0.19.0
> Environment: Cluster Capacity Maps=Reduces =210 each
> Two Queues:
> Q1: default, GC (%) =40, GC=84 (Maps and Reduces each). Reclaim time = 3
> mins.
> Q2: test_q1, GC (%) =60, GC=126 (Maps and Reduces each) Reclaim time = 2 mins
> Reporter: Karam Singh
> Assignee: Amar Kamat
> Attachments: 4558.1.patch, HADOOP-4558-v1.4.patch
>
>
> Scheduler fails to reclaim capacity if Jobs are submitted to queue one after
> the other.
> First job submitted with tasks equal to cluster's M/R Capacity
> Second is submitted to different queue when all tasks of First Job are
> running, scheduler fails to reclaim capacity for second job.
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