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https://issues.apache.org/jira/browse/HADOOP-11361?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vinayakumar B updated HADOOP-11361:
-----------------------------------
Attachment: HADOOP-11361-005.patch
bq. It looks to me that the acquirement of lastRecs and the updateAttrCache
should be protected in a same synchronized(this) block, to avoid this race
condition
In that case, there is no need to have a field {{lastRecs}}.
{{lastRecs}} was used only in {{updateAttrCache()}} and {{updateInfoCache()}}.
We can have the method local lastRecs and same can be passed to
{{updateAttrCache()}} and {{updateInfoCache()}}.
{{getMetrics()}} can return just {{builder.getRecords()}}.
So total number of {{synchronized}} calls will be reduced.
Attaching the proposed changes.
> 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.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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