[jira] [Commented] (HADOOP-9618) Add thread which detects JVM pauses

["Todd Lipcon (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-9618?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13674684#comment-13674684 ] 

Todd Lipcon commented on HADOOP-9618:
-------------------------------------

BTW, the info reported from the beans seems to be off due to an OpenJDK bug. When I run the same test program with Oracle JDK 1.6.0_14 I get correct stats from the CMS MXBean:

13/06/04 11:36:33 INFO util.JvmPauseMonitor: Detected pause in JVM or host machine (eg GC): pause of approximately 3232ms
GC pool 'ParNew' had collection(s): count=1 time=56ms
GC pool 'ConcurrentMarkSweep' had collection(s): count=1 time=3665ms

                
> Add thread which detects JVM pauses
> -----------------------------------
>
>                 Key: HADOOP-9618
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9618
>             Project: Hadoop Common
>          Issue Type: New Feature
>          Components: util
>    Affects Versions: 3.0.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>         Attachments: hadoop-9618.txt
>
>
> Often times users struggle to understand what happened when a long JVM pause (GC or otherwise) causes things to malfunction inside a Hadoop daemon. For example, a long GC pause while logging an edit to the QJM may cause the edit to timeout, or a long GC pause may make other IPCs to the NameNode timeout. We should add a simple thread which loops on 1-second sleeps, and if the sleep ever takes significantly longer than 1 second, log a WARN. This will make GC pauses obvious in logs.

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