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https://issues.apache.org/jira/browse/HBASE-28894?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wellington Chevreuil resolved HBASE-28894.
------------------------------------------
Resolution: Fixed
Merged to master, branch-3, branch-2 and branch-2.6.
> NPE on TestPrefetch.testPrefetchWithDelay
> -----------------------------------------
>
> Key: HBASE-28894
> URL: https://issues.apache.org/jira/browse/HBASE-28894
> Project: HBase
> Issue Type: Bug
> Affects Versions: 3.0.0-beta-1, 2.7.0
> Reporter: Wellington Chevreuil
> Assignee: Wellington Chevreuil
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.0.0, 2.7.0, 2.6.2
>
>
> I'm seeing some failures on TestPrefetch.testPrefetchWithDelay in some
> pre-commit runs, I believe this is due to a race condition in
> PrefetchExecutor.
> loadConfiguration.
> In these failures, it seems we are getting the NPE below:
> {noformat}
> Stacktracejava.lang.NullPointerException
> at
> java.util.concurrent.ConcurrentSkipListMap.put(ConcurrentSkipListMap.java:1580)
> at
> org.apache.hadoop.hbase.io.hfile.PrefetchExecutor.request(PrefetchExecutor.java:108)
> at
> org.apache.hadoop.hbase.io.hfile.PrefetchExecutor.lambda$loadConfiguration$0(PrefetchExecutor.java:206)
> at
> java.util.concurrent.ConcurrentSkipListMap.forEach(ConcurrentSkipListMap.java:3269)
> at
> org.apache.hadoop.hbase.io.hfile.PrefetchExecutor.loadConfiguration(PrefetchExecutor.java:200)
> at
> org.apache.hadoop.hbase.regionserver.PrefetchExecutorNotifier.onConfigurationChange(PrefetchExecutorNotifier.java:51)
> at
> org.apache.hadoop.hbase.io.hfile.TestPrefetch.testPrefetchWithDelay(TestPrefetch.java:378)
> {noformat}
> I think this is because we are completing prefetch in this test before the
> induced delay, then this test triggers a new configuration change, but the
> prefetch thread calls PrefetchExecutor.complete just before the test thread
> reaches [this
> point|https://github.com/apache/hbase/blob/master/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/PrefetchExecutor.java#L206]:
> {noformat}
> 2024-10-01T11:28:10,660 DEBUG [Time-limited test {}]
> hfile.PrefetchExecutor(102): Prefetch requested for
> /home/jenkins/jenkins-home/workspace/Base-PreCommit-GitHub-PR_PR-6328/yetus-jdk8-hadoop2-check/src/hbase-server/target/test-data/b646497b-7616-6533-e8cb-98e5c9e2e083/TestPrefetchWithDelay/71eefdb271ae4f65b694a6ec3d4287a0,
> delay=25000 ms
> 2024-10-01T11:28:30,668 INFO [Time-limited test {}] hbase.Waiter(181):
> Waiting up to [10,000] milli-secs(wait.for.ratio=[1])
> 2024-10-01T11:28:35,661 DEBUG [hfile-prefetch-1727782088576 {}]
> hfile.HFilePreadReader$1(103): No entry in the backing map for cache key
> 71eefdb271ae4f65b694a6ec3d4287a0_0.
> ...
> 2024-10-01T11:28:35,673 DEBUG [hfile-prefetch-1727782088576 {}]
> hfile.HFilePreadReader$1(103): No entry in the backing map for cache key
> 71eefdb271ae4f65b694a6ec3d4287a0_52849.
> 2024-10-01T11:28:35,674 DEBUG [Time-limited test {}]
> hfile.PrefetchExecutor(142): Prefetch cancelled for
> /home/jenkins/jenkins-home/workspace/Base-PreCommit-GitHub-PR_PR-6328/yetus-jdk8-hadoop2-check/src/hbase-server/target/test-data/b646497b-7616-6533-e8cb-98e5c9e2e083/TestPrefetchWithDelay/71eefdb271ae4f65b694a6ec3d4287a0
> 2024-10-01T11:28:35,674 DEBUG [hfile-prefetch-1727782088576 {}]
> hfile.PrefetchExecutor(121): Prefetch completed for
> 71eefdb271ae4f65b694a6ec3d4287a0
> 2024-10-01T11:28:35,674 DEBUG [Time-limited test {}]
> hfile.PrefetchExecutor(102): Prefetch requested for
> /home/jenkins/jenkins-home/workspace/Base-PreCommit-GitHub-PR_PR-6328/yetus-jdk8-hadoop2-check/src/hbase-server/target/test-data/b646497b-7616-6533-e8cb-98e5c9e2e083/TestPrefetchWithDelay/71eefdb271ae4f65b694a6ec3d4287a0,
> delay=991 ms
> ...
> {noformat}
> CC: [~kabhishek4]
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