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https://issues.apache.org/jira/browse/KAFKA-19334?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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TengYao Chi resolved KAFKA-19334.
---------------------------------
Resolution: Fixed
> MetadataShell bypasses file lock unexpectedly due to lock file deletion
> -----------------------------------------------------------------------
>
> Key: KAFKA-19334
> URL: https://issues.apache.org/jira/browse/KAFKA-19334
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 4.0.0
> Reporter: Haruki Okada
> Assignee: Haruki Okada
> Priority: Major
> Fix For: 3.9.2, 4.0.1, 4.1.0
>
>
> MetadataShell acquires log dir lock to prevent unexpected results by
> concurrent reads/writes fixed by [https://github.com/apache/kafka/pull/14899].
>
> This lock works as expected when we execute MetadataShell against running log
> for the first time:
>
> {code:java}
> % ./bin/kafka-metadata-shell.sh --snapshot data/bootstrap.checkpoint
> Unexpected error: Unable to lock /path/to/data. Please ensure that no broker
> or controller process is using this directory before proceeding.{code}
> However, if we execute MetadataShell with same command again with controller
> still running, it succeeds unexpectedly.
>
>
> {code:java}
> % ./bin/kafka-metadata-shell.sh --snapshot data/bootstrap.checkpoint
> Loading...
> Starting...
> [ Kafka Metadata Shell ]
> >> {code}
> And I found that .lock file vanishes after MetadataShell exit.
>
> This is because MetadataShell calls FileLock#destroy when it fails acquiring
> lock, which deletes the lock file.
> [https://github.com/apache/kafka/blob/4.0.0/shell/src/main/java/org/apache/kafka/shell/MetadataShell.java#L131]
>
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