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https://issues.apache.org/jira/browse/HADOOP-19049?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17812117#comment-17812117
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ASF GitHub Bot commented on HADOOP-19049:
-----------------------------------------
Hisoka-X commented on code in PR #6488:
URL: https://github.com/apache/hadoop/pull/6488#discussion_r1470514489
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java:
##########
@@ -4077,6 +4077,7 @@ private interface StatisticsAggregator<T> {
STATS_DATA_CLEANER.
setName(StatisticsDataReferenceCleaner.class.getName());
STATS_DATA_CLEANER.setDaemon(true);
+ STATS_DATA_CLEANER.setContextClassLoader(null);
Review Comment:
If the thread relies on the return value of
`Thread.currentThread().getContextClassLoader()` for logical processing, it may
encounter NPE, but I checked the corresponding code. This risk should not
exist. In fact, this is a normal way of handling classloader references in the
daemon thread. You can refer
https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-7008595
> Class loader leak caused by StatisticsDataReferenceCleaner thread
> -----------------------------------------------------------------
>
> Key: HADOOP-19049
> URL: https://issues.apache.org/jira/browse/HADOOP-19049
> Project: Hadoop Common
> Issue Type: Bug
> Components: common
> Affects Versions: 3.3.6
> Reporter: Jia Fan
> Priority: Major
> Labels: pull-request-available
>
> The
> "org.apache.hadoop.fs.FileSystem$Statistics$StatisticsDataReferenceCleaner"
> daemon thread was created by FileSystem.
> This is fine if the thread's context class loader is the system class loader,
> but it's bad if the context class loader is a custom class loader. The
> reference held by this daemon thread means that the class loader can never
> become eligible for GC.
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