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https://issues.apache.org/jira/browse/HADOOP-11361?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15374170#comment-15374170
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Tsuyoshi Ozawa edited comment on HADOOP-11361 at 7/13/16 2:06 AM:
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3. How about adding a comment why we release lock before calling private
method {{getMetrics}} in {{updateJmxCache}}?
{code}
// HADOOP-11361: Release lock here for avoid deadlock between
// MetricsSystemImpl's lock and MetricsSourceAdapter's lock.
List<MetricsRecordImpl> lastRecs = null;
if (getAllMetrics) {
lastRecs = getMetrics(new MetricsCollectorImpl());
}
{code}
was (Author: ozawa):
3. How about adding a comment why we release lock before calling {{getMetrics}}
private method in {{updateJmxCache}}?
{code}
// HADOOP-11361: Release lock here for avoid deadlock between
// MetricsSystemImpl's lock and MetricsSourceAdapter's lock.
List<MetricsRecordImpl> lastRecs = null;
if (getAllMetrics) {
lastRecs = getMetrics(new MetricsCollectorImpl());
}
{code}
> 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.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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