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HADOOP-19049. Fix StatisticsDataReferenceCleaner classloader leak #6488

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Merged
merged 4 commits into from
Feb 3, 2024
Merged

HADOOP-19049. Fix StatisticsDataReferenceCleaner classloader leak #6488

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HADOOP-19049. Fix StatisticsDataReferenceCleaner classloader leak
Hisoka-X Jan 23, 2024
496ed2c
update
Hisoka-X Feb 1, 2024
b4502bc
update
Hisoka-X Feb 1, 2024
114bd63
update
Hisoka-X Feb 1, 2024
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1 change: 1 addition & 0 deletions hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
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@steveloughran steveloughran Jan 29, 2024

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what are the risks of setting this to null?

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@Hisoka-X Hisoka-X Jan 30, 2024

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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

STATS_DATA_CLEANER.start();
}

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9 changes: 9 additions & 0 deletions ...ect/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFileSystemStorageStatistics.java
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Expand Up @@ -34,6 +34,7 @@

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNull;

/**
* This tests basic operations of {@link FileSystemStorageStatistics} class.
Expand Down Expand Up @@ -102,6 +103,14 @@ public void testGetLong() {
}
}

@Test
public void testStatisticsDataReferenceCleanerClassLoader() {
Thread thread = Thread.getAllStackTraces().keySet().stream()
.filter(t -> t.getName().contains("StatisticsDataReferenceCleaner")).findFirst().get();
ClassLoader classLoader = thread.getContextClassLoader();
assertNull(classLoader);
}

/**
* Helper method to retrieve the specific FileSystem.Statistics value by name.
*
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