diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 7950b09078b..3d60e9567ba 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -384,6 +384,9 @@ Release 2.4.0 - UNRELEASED
     HADOOP-10368. InputStream is not closed in VersionInfo ctor.
     (Tsuyoshi OZAWA via szetszwo)
 
+    HADOOP-10368. FsUrlStreamHandlerFactory is not thread safe.
+    (Tudor Scurtu via cnauroth)
+
   BREAKDOWN OF HADOOP-10184 SUBTASKS AND RELATED JIRAS
 
     HADOOP-10185. FileSystem API for ACLs. (cnauroth)
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsUrlStreamHandlerFactory.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsUrlStreamHandlerFactory.java
index 9c212a4a59d..91a527dce7e 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsUrlStreamHandlerFactory.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsUrlStreamHandlerFactory.java
@@ -19,8 +19,8 @@ package org.apache.hadoop.fs;
 
 import java.io.IOException;
 import java.net.URLStreamHandlerFactory;
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
@@ -45,7 +45,8 @@ public class FsUrlStreamHandlerFactory implements
   private Configuration conf;
 
   // This map stores whether a protocol is know or not by FileSystem
-  private Map<String, Boolean> protocols = new HashMap<String, Boolean>();
+  private Map<String, Boolean> protocols =
+      new ConcurrentHashMap<String, Boolean>();
 
   // The URL Stream handler
   private java.net.URLStreamHandler handler;
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestUrlStreamHandler.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestUrlStreamHandler.java
index 845eb6314ef..0871f6edd9c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestUrlStreamHandler.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestUrlStreamHandler.java
@@ -35,7 +35,7 @@ import org.apache.hadoop.test.PathUtils;
 import org.junit.Test;
 
 /**
- * Test of the URL stream handler factory.
+ * Test of the URL stream handler.
  */
 public class TestUrlStreamHandler {
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestUrlStreamHandlerFactory.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestUrlStreamHandlerFactory.java
new file mode 100644
index 00000000000..910fee2b071
--- /dev/null
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestUrlStreamHandlerFactory.java
@@ -0,0 +1,80 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.fs;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Random;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Test of the URL stream handler factory.
+ */
+public class TestUrlStreamHandlerFactory {
+
+  private static final int RUNS = 20;
+  private static final int THREADS = 10;
+  private static final int TASKS = 200;
+  private static final int TIMEOUT = 30;
+
+  @Test
+  public void testConcurrency() throws Exception {
+    for (int i = 0; i < RUNS; i++) {
+      singleRun();
+    }
+  }
+
+  private void singleRun() throws Exception {
+    final FsUrlStreamHandlerFactory factory = new FsUrlStreamHandlerFactory();
+    final Random random = new Random();
+    ExecutorService executor = Executors.newFixedThreadPool(THREADS);
+    ArrayList<Future<?>> futures = new ArrayList<Future<?>>(TASKS);
+
+    for (int i = 0; i < TASKS ; i++) {
+      final int aux = i;
+      futures.add(executor.submit(new Runnable() {
+        @Override
+        public void run() {
+          int rand = aux + random.nextInt(3);
+          factory.createURLStreamHandler(String.valueOf(rand));
+        }
+      }));
+    }
+
+    executor.shutdown();
+    try {
+      executor.awaitTermination(TIMEOUT, TimeUnit.SECONDS);
+      executor.shutdownNow();
+    } catch (InterruptedException e) {
+      // pass
+    }
+
+    // check for exceptions
+    for (Future future : futures) {
+      if (!future.isDone()) {
+        break; // timed out
+      }
+      future.get();
+    }
+  }
+}