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HADOOP-15331. Fix a race condition causing parsing error of java.io.BufferedInputStream in class org.apache.hadoop.conf.Configuration. Contributed by Miklos Szegedi. 

(cherry picked from commit 268c29a5f5)
This commit is contained in:
Yufei Gu 2018-03-22 11:04:37 -07:00 committed by Akira Ajisaka
parent 0d88d832cd
commit 68ac742d94
2 changed files with 34 additions and 1 deletions
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5
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
View File

@ -768,8 +768,11 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
*/
@SuppressWarnings("unchecked")
public Configuration(Configuration other) {
this.resources = (ArrayList<Resource>) other.resources.clone();
synchronized(other) {
// Make sure we clone a finalized state
// Resources like input streams can be processed only once
other.getProps();
this.resources = (ArrayList<Resource>) other.resources.clone();
if (other.properties != null) {
this.properties = (Properties)other.properties.clone();
}

30
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestConfiguration.java
View File

@ -2142,4 +2142,34 @@ public class TestConfiguration extends TestCase {
assertEquals(" prefix >cdata\nsuffix ", conf.get("cdata-whitespace"));
return conf;
}
/**
* Test race conditions between clone() and getProps().
* Test for race conditions in the way Hadoop handles the Configuration
* class. The scenario is the following. Let's assume that there are two
* threads sharing the same Configuration class. One adds some resources
* to the configuration, while the other one clones it. Resources are
* loaded lazily in a deferred call to loadResources(). If the cloning
* happens after adding the resources but before parsing them, some temporary
* resources like input stream pointers are cloned. Eventually both copies
* will load the same input stream resources.
* One parses the input stream XML and closes it updating it's own copy of
* the resource. The other one has another pointer to the same input stream.
* When it tries to load it, it will crash with a stream closed exception.
*/
@Test
public void testResourceRace() {
InputStream is =
new BufferedInputStream(new ByteArrayInputStream(
"<configuration></configuration>".getBytes()));
Configuration config = new Configuration();
// Thread 1
config.addResource(is);
// Thread 2
Configuration confClone = new Configuration(conf);
// Thread 2
confClone.get("firstParse");
// Thread 1
config.get("secondParse");
}
}