Revert "HADOOP-11274. ConcurrentModificationException in Configuration Copy Constructor. Contributed by Junping Du."

This reverts commit 16b3482467.

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -910,9 +910,6 @@ Release 2.6.0 - UNRELEASED
     HADOOP-11253. Hadoop streaming test TestStreamXmlMultipleRecords fails on
     Windows. (Varun Vasudev via wheat9)
 
-    HADOOP-11274. ConcurrentModificationException in Configuration Copy Constructor.
-    (Junping Du via jing9)
-
     BREAKDOWN OF HDFS-6134 AND HADOOP-10150 SUBTASKS AND RELATED JIRAS
   
       HADOOP-10734. Implement high-performance secure random number sources.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java

@@ -690,8 +690,8 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
    */
   @SuppressWarnings("unchecked")
   public Configuration(Configuration other) {
-    synchronized(other) {
    this.resources = (ArrayList<Resource>) other.resources.clone();
+   synchronized(other) {
      if (other.properties != null) {
        this.properties = (Properties)other.properties.clone();
      }
@@ -702,14 +702,14 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
 
      this.updatingResource = new HashMap<String, String[]>(other.updatingResource);
      this.finalParameters = new HashSet<String>(other.finalParameters);
-
-      this.classLoader = other.classLoader;
-      this.loadDefaults = other.loadDefaults;
-      setQuietMode(other.getQuietMode());
    }
+   
     synchronized(Configuration.class) {
       REGISTRY.put(this, null);
     }
+    this.classLoader = other.classLoader;
+    this.loadDefaults = other.loadDefaults;
+    setQuietMode(other.getQuietMode());
   }
   
   /**
@@ -1025,7 +1025,6 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
     getProps().setProperty(name, value);
     String newSource = (source == null ? "programmatically" : source);
 
-    synchronized (this) {
     if (!isDeprecated(name)) {
       updatingResource.put(name, new String[] {newSource});
       String[] altNames = getAlternativeNames(name);
@@ -1049,7 +1048,6 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
       }
     }
   }
-  }
 
   private void warnOnceIfDeprecated(DeprecationContext deprecations, String name) {
     DeprecatedKeyInfo keyInfo = deprecations.getDeprecatedKeyMap().get(name);
@@ -2279,7 +2277,7 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
    *
    * @return final parameter set.
    */
-  public synchronized Set<String> getFinalParameters() {
+  public Set<String> getFinalParameters() {
     return new HashSet<String>(finalParameters);
   }
 
@@ -2542,20 +2540,16 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
     if (value != null) {
       if (!finalParameters.contains(attr)) {
         properties.setProperty(attr, value);
-        synchronized(this) {
         updatingResource.put(attr, source);
-        }
       } else if (!value.equals(properties.getProperty(attr))) {
         LOG.warn(name+":an attempt to override final parameter: "+attr
             +";  Ignoring.");
       }
     }
     if (finalParameter) {
-      synchronized(this) {
       finalParameters.add(attr);
     }
   }
-  }
 
   /** 
    * Write out the non-default properties in this configuration to the given
@@ -2747,7 +2741,7 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
   }
 
   @Override
-  public synchronized void readFields(DataInput in) throws IOException {
+  public void readFields(DataInput in) throws IOException {
     clear();
     int size = WritableUtils.readVInt(in);
     for(int i=0; i < size; ++i) {
@@ -2759,8 +2753,9 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
     }
   }
 
+  //@Override
   @Override
-  public synchronized void write(DataOutput out) throws IOException {
+  public void write(DataOutput out) throws IOException {
     Properties props = getProps();
     WritableUtils.writeVInt(out, props.size());
     for(Map.Entry<Object, Object> item: props.entrySet()) {