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https://issues.apache.org/jira/browse/HADOOP-9128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13536807#comment-13536807
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Luke Lu commented on HADOOP-9128:
---------------------------------
Apache Hadoop 1.0+ use metrics2, which doesn't use MetricsDynamicMBeanBase.
It'll be interesting to see if such case can happen in recent versions of
Hadoop.
> MetricsDynamicMBeanBase can cause high cpu load
> -----------------------------------------------
>
> Key: HADOOP-9128
> URL: https://issues.apache.org/jira/browse/HADOOP-9128
> Project: Hadoop Common
> Issue Type: Bug
> Components: metrics
> Affects Versions: 0.20.2
> Environment: cdh3u4
> Reporter: Nate Putnam
>
> I noticed high load on some of our Hadoop services. On closer inspection we
> found several threads that were consuming cpu (80-90% of a core) doing :
> java.lang.Thread.State: RUNNABLE
> at java.util.HashMap.get(HashMap.java:303)
> at
> org.apache.hadoop.metrics.util.MetricsDynamicMBeanBase.getAttribute(MetricsDynamicMBeanBase.java:135)
> at
> com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getAttribute(DefaultMBeanServerInterceptor.java:666)
> This is a known issue in java when using a non thread safe hash map from
> multiple threads.
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