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From "Ted Yu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14268) Improve KeyLocker
Date Sun, 23 Aug 2015 01:01:45 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14708249#comment-14708249

Ted Yu commented on HBASE-14268:

+            public ReentrantLock createObject(K key) { return new ReentrantLock(); }
Put return statement on second line and right curly on 3rd line.
+   * @throws IllegalArgumentException if {@code initCapacity} is negative
+   * @throws NullPointerException if {@code objectFactory} is null
+   */
+  public WeakObjectPool(int initCapacity, ObjectFactory<K, V> objectFactory) {
Add javadoc for parameters.
+    this.referenceCache = new ConcurrentHashMap<K, ObjectReference>(initCapacity);
+    if (objectFactory == null) { throw new NullPointerException(); }
Suggest moving null check ahead of HashMap creation.

> 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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