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https://issues.apache.org/jira/browse/YARN-4210?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14935165#comment-14935165
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Varun Saxena commented on YARN-4210:
------------------------------------
Moreover, there are couple of other issues I noticed while going through the
code.
# I cannot see ResultScanner#close being called in xxxEntityReader classes.
Depending on number of queries going on in parallel, this may become an issue
at server side. Server will expire the scanner after a configured lease
interval if close is not called explicitly.
# Also is FlowActivityEntityReader#readEntities required ?
TimelineEntityReader#readEntities should suffice. In
TimelineEntityReader#readEntities though we can check when we reach the limit
instead of going over limit and then calling pollLast. In short follow same
approach as FlowActivityEntityReader,
cc [~sjlee0], [~vrushalic], [~jrottinghuis].
> HBase reader throws NPE if Get returns no rows
> ----------------------------------------------
>
> Key: YARN-4210
> URL: https://issues.apache.org/jira/browse/YARN-4210
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: timelineserver
> Affects Versions: YARN-2928
> Reporter: Varun Saxena
> Assignee: Varun Saxena
> Attachments: YARN-4210-YARN-2928.01.patch
>
>
> If HBase Get does not fetch any rows for the query, we still try to parse the
> result and read fields. This leads to NPE while reading metrics. We should
> not attempt to read anything if no row is returned i.e. result is empty.
> Found during web UI poc testing.
> {noformat}
> 2015-09-29 20:22:32,027 ERROR [95336304@qtp-1814206058-0]
> reader.TimelineReaderWebServices
> (TimelineReaderWebServices.java:handleException(199)) - Error while
> processing REST request
> java.lang.NullPointerException
> at
> org.apache.hadoop.yarn.server.timelineservice.storage.common.ColumnHelper.readResultsWithTimestamps(ColumnHelper.java:176)
> at
> org.apache.hadoop.yarn.server.timelineservice.storage.flow.FlowRunColumnPrefix.readResultsWithTimestamps(FlowRunColumnPrefix.java:182)
> at
> org.apache.hadoop.yarn.server.timelineservice.storage.TimelineEntityReader.readMetrics(TimelineEntityReader.java:212)
> at
> org.apache.hadoop.yarn.server.timelineservice.storage.FlowRunEntityReader.parseEntity(FlowRunEntityReader.java:136)
> at
> org.apache.hadoop.yarn.server.timelineservice.storage.TimelineEntityReader.readEntity(TimelineEntityReader.java:137)
> at
> org.apache.hadoop.yarn.server.timelineservice.storage.HBaseTimelineReaderImpl.getEntity(HBaseTimelineReaderImpl.java:72)
> at
> org.apache.hadoop.yarn.server.timelineservice.reader.TimelineReaderManager.getEntity(TimelineReaderManager.java:93)
> at
> org.apache.hadoop.yarn.server.timelineservice.reader.TimelineReaderWebServices.getFlowRun(TimelineReaderWebServices.java:403)
> {noformat}
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