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From "Yongjun Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-11361) Fix a race condition in MetricsSourceAdapter.updateJmxCache
Date Wed, 13 Jul 2016 05:40:20 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-11361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15374384#comment-15374384
] 

Yongjun Zhang commented on HADOOP-11361:
----------------------------------------

Thanks guys, that's another improvement!

One little thing:
{code}
    synchronized (this) {
      if (lastRecs != null) {
        updateAttrCache(lastRecs);
        if (getAllMetrics) {  <====== this check is redundant
          updateInfoCache(lastRecs);
        }
      }
      jmxCacheTS = Time.now();
      lastRecsCleared = true;
    }
{code}
The {{if (getAllMetrics)}} in the above code is redundant, because it has to be true when
{{lastRecs}} is not null.

Thanks.


> Fix a race condition in MetricsSourceAdapter.updateJmxCache
> -----------------------------------------------------------
>
>                 Key: HADOOP-11361
>                 URL: https://issues.apache.org/jira/browse/HADOOP-11361
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 2.4.1, 2.5.1, 2.6.0
>            Reporter: Brahma Reddy Battula
>            Assignee: Brahma Reddy Battula
>         Attachments: HADOOP-111361-003.patch, HADOOP-11361-002.patch, HADOOP-11361-004.patch,
HADOOP-11361-005.patch, HADOOP-11361-005.patch, HADOOP-11361-006.patch, HADOOP-11361.patch,
HDFS-7487.patch
>
>
> {noformat}
> Caused by: java.lang.NullPointerException
> 	at org.apache.hadoop.metrics2.impl.MetricsSourceAdapter.updateAttrCache(MetricsSourceAdapter.java:247)
> 	at org.apache.hadoop.metrics2.impl.MetricsSourceAdapter.updateJmxCache(MetricsSourceAdapter.java:177)
> 	at org.apache.hadoop.metrics2.impl.MetricsSourceAdapter.getAttribute(MetricsSourceAdapter.java:102)
> 	at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getAttribute(DefaultMBeanServerInterceptor.java:647)
> {noformat}



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