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Date: Thu, 20 Aug 2015 16:17:46 +0000 (UTC)
From: "Ted Yu (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12857497.1440065558000.120845.1440087466022@Atlassian.JIRA>
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Subject: [jira] [Commented] (HBASE-14268) Improve KeyLocker
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    [ https://issues.apache.org/jira/browse/HBASE-14268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14705199#comment-14705199 ] 

Ted Yu commented on HBASE-14268:
--------------------------------

{code}
117	    ReentrantLock lock = getLock(key);
118	    purge();
{code}
Do we need to call purge() for every acquireLock() ?

> 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.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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