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https://issues.apache.org/jira/browse/HBASE-14268?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Hiroshi Ikeda updated HBASE-14268:
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Attachment: HBASE-14268-V3.patch
Added a revised patch.
Refactored; Extracted the logic around handling weak references to a new class
{{WeakObjectPool}}.
The similar class {{IdLock}} can be rewritten with {{WeakObjectPool}}, and its
variant class using {{ReadWriteLock}} instead of {{Lock}} can be easily created
if needed, I guess :-)
> Improve KeyLocker
> -----------------
>
> Key: HBASE-14268
> URL: https://issues.apache.org/jira/browse/HBASE-14268
> Project: HBase
> Issue Type: Improvement
> Components: util
> Reporter: Hiroshi Ikeda
> Assignee: Hiroshi Ikeda
> Priority: Minor
> Attachments: HBASE-14268-V2.patch, HBASE-14268-V3.patch,
> HBASE-14268.patch, KeyLockerPerformance.java
>
>
> 1. In the implementation of {{KeyLocker}} it uses atomic variables inside a
> synchronized block, which doesn't make sense. Moreover, logic inside the
> synchronized block is not trivial so that it makes less performance in heavy
> multi-threaded environment.
> 2. {{KeyLocker}} gives an instance of {{RentrantLock}} which is already
> locked, but it doesn't follow the contract of {{ReentrantLock}} because you
> are not allowed to freely invoke lock/unlock methods under that contract.
> That introduces a potential risk; Whenever you see a variable of the type
> {{RentrantLock}}, you should pay attention to what the included instance is
> coming from.
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