[jira] [Commented] (HADOOP-8684) Deadlock between WritableComparator and WritableComparable

["Hadoop QA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-8684?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13443902#comment-13443902 ] 

Hadoop QA commented on HADOOP-8684:
-----------------------------------

-1 overall.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12542865/Hadoop-8684.patch
  against trunk revision .

    +1 @author.  The patch does not contain any @author tags.

    -1 tests included.  The patch doesn't appear to include any new or modified tests.
                        Please justify why no new tests are needed for this patch.
                        Also please list what manual steps were performed to verify this patch.

    +1 javac.  The applied patch does not increase the total number of javac compiler warnings.

    +1 javadoc.  The javadoc tool did not generate any warning messages.

    +1 eclipse:eclipse.  The patch built with eclipse:eclipse.

    +1 findbugs.  The patch does not introduce any new Findbugs (version 1.3.9) warnings.

    +1 release audit.  The applied patch does not increase the total number of release audit warnings.

    +1 core tests.  The patch passed unit tests in hadoop-common-project/hadoop-common.

    +1 contrib tests.  The patch passed contrib unit tests.

Test results: https://builds.apache.org/job/PreCommit-HADOOP-Build/1378//testReport/
Console output: https://builds.apache.org/job/PreCommit-HADOOP-Build/1378//console

This message is automatically generated.
                
> Deadlock between WritableComparator and WritableComparable
> ----------------------------------------------------------
>
>                 Key: HADOOP-8684
>                 URL: https://issues.apache.org/jira/browse/HADOOP-8684
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: io
>    Affects Versions: 1.0.3, 3.0.0
>            Reporter: Hiroshi Ikeda
>            Assignee: Jing Zhao
>            Priority: Minor
>         Attachments: Hadoop-8684.patch, WritableComparatorDeadLockTestApp.java
>
>
> Classes implementing WriableComparable in Hadoop call the method WritableComparator.define() in their static initializers. This means, the classes call the method define() while thier class loading, under locking their class objects. And, the method WritableComparator.define() locks the WritableComaprator class object.
> On the other hand, WritableComparator.get() also locks the WritableComparator class object, and the method may create instances of the targeted comparable class, involving loading the targeted comparable class if any. This means, the method might try to lock the targeted comparable class object under locking the WritableComparator class object.
> There are reversed orders of locking objects, and you might fall in deadlock.

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