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https://issues.apache.org/jira/browse/MAPREDUCE-7173?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mikayla Konst updated MAPREDUCE-7173:
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Attachment: MAPREDUCE-7173.patch
Status: Patch Available (was: Open)
> Add ability to shuffle intermediate map task output to a distributed
> filesystem
> -------------------------------------------------------------------------------
>
> Key: MAPREDUCE-7173
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-7173
> Project: Hadoop Map/Reduce
> Issue Type: New Feature
> Components: mrv2
> Affects Versions: 2.9.2
> Reporter: Mikayla Konst
> Priority: Major
> Attachments: MAPREDUCE-7173.patch
>
>
> If nodes are lost during the course of a mapreduce job, the map tasks that
> ran on those nodes need to be re-run. Writing intermediate map task output to
> a distributed file system eliminates this problem in environments in which
> nodes are frequently lost, for example, in clusters that make heavy use of
> Google's Preemptible VMs or AWS's Spot Instances.
> *Example Usage:*
> *Job-scoped properties:*
> 1. Don't re-run an already-finished map task when we realize the node it ran
> on is now unusable:
> mapreduce.map.rerun-if-node-unusable=false (see MAPREDUCE-7168)
> 2. On the map side, use a new implementation of MapOutputFile that provides
> paths relative to the staging dir for the job (which is cleaned up when the
> job is done):
> mapreduce.task.general.output.class=org.apache.hadoop.mapred.HCFSOutputFiles
> 3. On the reduce side, use a new implementation of ShuffleConsumerPlugin that
> fetches map task output directly from a distributed filesystem:
> mapreduce.job.reduce.shuffle.consumer.plugin.class=org.apache.hadoop.mapreduce.task.reduce.HCFSShuffle
> 4. (Optional) Edit the buffer size for the output stream used when writing
> map task output
> mapreduce.map.shuffle.output.buffer.size=8192
> *Cluster-scoped properties* (see YARN-9106):
> 1. When gracefully decommissioning a node, only wait for the containers on
> that node to finish, not the applications associated with those containers
> (we don't need to wait on the applications to finish since this node is not
> serving shuffle data)
> yarn.resourcemanager.decommissioning-nodes-watcher.wait-for-applications=false
> 2. When gracefully decommissioning a node, do not wait for app masters
> running on the node to finish so that this node can be decommissioned as soon
> as possible (failover to an app master on another node that isn't being
> decommissioned is pretty quick)
> yarn.resourcemanager.decommissioning-nodes-watcher.wait-for-app-masters=false
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