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https://issues.apache.org/jira/browse/HDFS-17098?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17846546#comment-17846546
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ASF GitHub Bot commented on HDFS-17098:
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Hexiaoqiao commented on PR #6035:
URL: https://github.com/apache/hadoop/pull/6035#issuecomment-2111897786
@teamconfx Would you mind to fix the checkstyle before checkin?
> DatanodeManager does not handle null storage type properly
> ----------------------------------------------------------
>
> Key: HDFS-17098
> URL: https://issues.apache.org/jira/browse/HDFS-17098
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: ConfX
> Priority: Critical
> Labels: pull-request-available
> Attachments: reproduce.sh
>
>
> h2. What happened:
> Got a {{NullPointerException}} without message when sorting datanodes in
> {{{}NetworkTopology{}}}.
> h2. Where's the bug:
> In line 654 of {{{}DatanodeManager{}}}, the manager creates a second sorter
> using the standard {{Comparator}} class:
> {noformat}
> Comparator<DatanodeInfoWithStorage> comp =
> Comparator.comparing(DatanodeInfoWithStorage::getStorageType);
> secondarySort = list -> Collections.sort(list, comp);{noformat}
> This comparator is then used in {{NetworkTopology}} as a secondary sort to
> break ties:
> {noformat}
> if (secondarySort != null) {
> // a secondary sort breaks the tie between nodes.
> secondarySort.accept(nodesList);
> }{noformat}
> However, if the storage type is {{{}null{}}}, a {{NullPointerException}}
> would be thrown since the default {{Comparator.comparing}} cannot handle
> comparison between null values.
> h2. How to reproduce:
> (1) Set {{dfs.heartbeat.interval}} to {{{}1753310367{}}}, and
> {{dfs.namenode.read.considerStorageType}} to {{true}}
> (2) Run test:
> {{org.apache.hadoop.hdfs.server.blockmanagement.TestSortLocatedBlock#testAviodStaleAndSlowDatanodes}}
> h2. Stacktrace:
> {noformat}
> java.lang.NullPointerException
> at
> java.base/java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469)
> at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
> at java.base/java.util.TimSort.sort(TimSort.java:220)
> at java.base/java.util.Arrays.sort(Arrays.java:1515)
> at java.base/java.util.ArrayList.sort(ArrayList.java:1750)
> at java.base/java.util.Collections.sort(Collections.java:179)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager.lambda$createSecondaryNodeSorter$0(DatanodeManager.java:654)
> at
> org.apache.hadoop.net.NetworkTopology.sortByDistance(NetworkTopology.java:983)
> at
> org.apache.hadoop.net.NetworkTopology.sortByDistanceUsingNetworkLocation(NetworkTopology.java:946)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager.sortLocatedBlock(DatanodeManager.java:637)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager.sortLocatedBlocks(DatanodeManager.java:554)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.TestSortLocatedBlock.testAviodStaleAndSlowDatanodes(TestSortLocatedBlock.java:144){noformat}
> For an easy reproduction, run the reproduce.sh in the attachment. We are
> happy to provide a patch if this issue is confirmed.
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