Merged r1208926 from trunk for HADOOP-7854.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1208929 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -51,8 +51,10 @@ Release 0.23.1 - Unreleased
    HADOOP-7864. Building mvn site with Maven < 3.0.2 causes OOM errors.
    (Andrew Bayer via eli)
 
-    HADOOP-7853. multiple javax security configurations cause conflicts.
-    (daryn via tucu)
+   HADOOP-7853. multiple javax security configurations cause conflicts.
+   (daryn via tucu)
+
+   HADOOP-7854. UGI getCurrentUser is not synchronized. (Daryn Sharp via jitendra)
 
 Release 0.23.0 - 2011-11-01 
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java

@@ -449,7 +449,8 @@ public class UserGroupInformation {
    * @return the current user
    * @throws IOException if login fails
    */
-  public static UserGroupInformation getCurrentUser() throws IOException {
+  public synchronized
+  static UserGroupInformation getCurrentUser() throws IOException {
     AccessControlContext context = AccessController.getContext();
     Subject subject = Subject.getSubject(context);
     if (subject == null || subject.getPrincipals(User.class).isEmpty()) {