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https://issues.apache.org/jira/browse/HADOOP-4665?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12671725#action_12671725
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Hadoop QA commented on HADOOP-4665:
-----------------------------------
-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12399789/hadoop-4665-v1b.patch
against trunk revision 742171.
+1 @author. The patch does not contain any @author tags.
+1 tests included. The patch appears to include 9 new or modified tests.
+1 javadoc. The javadoc tool did not generate any warning messages.
+1 javac. The applied patch does not increase the total number of javac
compiler warnings.
+1 findbugs. The patch does not introduce any new Findbugs warnings.
+1 Eclipse classpath. The patch retains Eclipse classpath integrity.
+1 release audit. The applied patch does not increase the total number of
release audit warnings.
-1 core tests. The patch failed core unit tests.
-1 contrib tests. The patch failed contrib unit tests.
Test results:
http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/3813/testReport/
Findbugs warnings:
http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/3813/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results:
http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/3813/artifact/trunk/build/test/checkstyle-errors.html
Console output:
http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/3813/console
This message is automatically generated.
> Add preemption to the fair scheduler
> ------------------------------------
>
> Key: HADOOP-4665
> URL: https://issues.apache.org/jira/browse/HADOOP-4665
> Project: Hadoop Core
> Issue Type: New Feature
> Components: contrib/fair-share
> Reporter: Matei Zaharia
> Attachments: fs-preemption-v0.patch, hadoop-4665-v1.patch,
> hadoop-4665-v1b.patch
>
>
> Task preemption is necessary in a multi-user Hadoop cluster for two reasons:
> users might submit long-running tasks by mistake (e.g. an infinite loop in a
> map program), or tasks may be long due to having to process large amounts of
> data. The Fair Scheduler (HADOOP-3746) has a concept of guaranteed capacity
> for certain queues, as well as a goal of providing good performance for
> interactive jobs on average through fair sharing. Therefore, it will support
> preempting under two conditions:
> 1) A job isn't getting its _guaranteed_ share of the cluster for at least T1
> seconds.
> 2) A job is getting significantly less than its _fair_ share for T2 seconds
> (e.g. less than half its share).
> T1 will be chosen smaller than T2 (and will be configurable per queue) to
> meet guarantees quickly. T2 is meant as a last resort in case non-critical
> jobs in queues with no guaranteed capacity are being starved.
> When deciding which tasks to kill to make room for the job, we will use the
> following heuristics:
> - Look for tasks to kill only in jobs that have more than their fair share,
> ordering these by deficit (most overscheduled jobs first).
> - For maps: kill tasks that have run for the least amount of time (limiting
> wasted time).
> - For reduces: similar to maps, but give extra preference for reduces in the
> copy phase where there is not much map output per task (at Facebook, we have
> observed this to be the main time we need preemption - when a job has a long
> map phase and its reducers are mostly sitting idle and filling up slots).
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