Hadoop JvmPauseMonitor
<p>Recently came across and interesting scenario with Cloudera Hadoop and HDFS where we were unable to start our NameNode Service.</p>

<p>When attempting a restart of HDFS Services we were unable successfully restart NameNode Service in our cluster.  Upon review of the logs, we did not observe any ERRORs but did see a few entries related to <code>JvmPauseMonitor</code>... </p>

<blockquote>
  <p>org.apache.hadoop.util.JvmPauseMonitor: Detected pause in JVM or host machine (eg GC): pause of approximately 5015ms</p>
</blockquote>

<p>We were observing these entries in the <code>/var/log/hadoop-hdfs/NAMENODE.log.out</code> and were not seeing any other errors including <code>/var/log/messages</code>.</p>