HBASE-10143 replace WritableFactories's hashmap with ConcurrentHashMap (Liang Xie via Stack)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1559923 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -113,6 +113,9 @@ Trunk (Unreleased)
 
     HADOOP-10177. Create CLI tools for managing keys. (Larry McCay via omalley)
 
+    HADOOP-10143 replace WritableFactories's hashmap with ConcurrentHashMap
+    (Liang Xie via stack)
+
   BUG FIXES
 
     HADOOP-9451. Fault single-layer config if node group topology is enabled.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableFactories.java

@@ -22,25 +22,26 @@ import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.*;
 import org.apache.hadoop.util.ReflectionUtils;
-import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 /** Factories for non-public writables.  Defining a factory permits {@link
  * ObjectWritable} to be able to construct instances of non-public classes. */
 @InterfaceAudience.Public
 @InterfaceStability.Stable
 public class WritableFactories {
-  private static final HashMap<Class, WritableFactory> CLASS_TO_FACTORY =
-    new HashMap<Class, WritableFactory>();
+  private static final Map<Class, WritableFactory> CLASS_TO_FACTORY =
+    new ConcurrentHashMap<Class, WritableFactory>();
 
   private WritableFactories() {}                  // singleton
 
   /** Define a factory for a class. */
-  public static synchronized void setFactory(Class c, WritableFactory factory) {
+  public static void setFactory(Class c, WritableFactory factory) {
     CLASS_TO_FACTORY.put(c, factory);
   }
 
   /** Define a factory for a class. */
-  public static synchronized WritableFactory getFactory(Class c) {
+  public static WritableFactory getFactory(Class c) {
     return CLASS_TO_FACTORY.get(c);
   }