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HADOOP-13500. Synchronizing iteration of Configuration properties object (#3775)

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Signed-off-by: Akira Ajisaka <aajisaka@apache.org>
(cherry picked from commit 4483607a4e)
This commit is contained in:
Dhananjay Badaya 2021-12-17 12:35:46 +05:30 committed by Akira Ajisaka
parent e60b8a0358
commit e7b1f87665
2 changed files with 35 additions and 4 deletions
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10
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
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@ -2956,13 +2956,15 @@ public Iterator<Map.Entry<String, String>> iterator() {
// methods that allow non-strings to be put into configurations are removed,
// we could replace properties with a Map<String,String> and get rid of this
// code.
Map<String,String> result = new HashMap<String,String>();
for(Map.Entry<Object,Object> item: getProps().entrySet()) {
if (item.getKey() instanceof String &&
item.getValue() instanceof String) {
Properties props = getProps();
Map<String, String> result = new HashMap<>();
synchronized (props) {
for (Map.Entry<Object, Object> item : props.entrySet()) {
if (item.getKey() instanceof String && item.getValue() instanceof String) {
result.put((String) item.getKey(), (String) item.getValue());
}
}
}
return result.entrySet().iterator();
}

29
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestConfiguration.java
View File

@ -38,6 +38,7 @@
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
@ -45,6 +46,7 @@
import java.util.Properties;
import java.util.Random;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.regex.Pattern;
import static java.util.concurrent.TimeUnit.*;
@ -2678,4 +2680,31 @@ private static Configuration checkCDATA(byte[] bytes) {
assertEquals(" prefix >cdata\nsuffix ", conf.get("cdata-whitespace"));
return conf;
}
@Test
public void testConcurrentModificationDuringIteration() throws InterruptedException {
Configuration configuration = new Configuration();
new Thread(() -> {
while (true) {
configuration.set(String.valueOf(Math.random()), String.valueOf(Math.random()));
}
}).start();
AtomicBoolean exceptionOccurred = new AtomicBoolean(false);
new Thread(() -> {
while (true) {
try {
configuration.iterator();
} catch (final ConcurrentModificationException e) {
exceptionOccurred.set(true);
break;
}
}
}).start();
Thread.sleep(1000); //give enough time for threads to run
assertFalse("ConcurrentModificationException occurred", exceptionOccurred.get());
}
}