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https://issues.apache.org/jira/browse/MAPREDUCE-6434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14707498#comment-14707498
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Chris Douglas commented on MAPREDUCE-6434:
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Agreed, the NPE is usually not a problem since the default should be defined in
mapred-defaults, though {{JobContextImpl::getReducerClass}} can return null. At
least two cases shouldn't cause a problem for map-only jobs:
# The base {{mapreduce.Reducer}} is {{\@Checkpointable}}, so it would
instantiate a {{PartialFileOutputCommitter}}
# A {{Reducer}} in the config shouldn't cause a map-only job to fail if it's
not on the classpath (this may not be true in the current code, but this
shouldn't add another case)
We also don't want to do anything surprising for setup/cleanup tasks.
> Add support for PartialFileOutputCommiter when checkpointing is an option
> during preemption
> -------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-6434
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6434
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Reporter: Augusto Souza
> Assignee: Augusto Souza
> Attachments: MAPREDUCE-6434.001.patch, MAPREDUCE-6434.002.patch,
> MAPREDUCE-6434.003.patch, MAPREDUCE-6434.004.patch, MAPREDUCE-6434.005.patch,
> MAPREDUCE-6434.006.patch
>
>
> Finish up some renaming work related to the annotation @Preemptable (it
> should be @Checkpointable now) and help in the splitting of patch in
> MAPREDUCE-5269 that is too large for being reviewed or accepted by Jenkins CI
> scripts.
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