commit a6803b0a30e5022e1b11930b900c8f70ac5cf80f

Author: Devaraj Das <ddas@yahoo-inc.com>
Date:   Fri Nov 19 18:52:25 2010 -0800

    . Fixes the relogin to do relogin even if the TGT is null. Contributed by Kan Zhang.
    
    +++ b/YAHOO-CHANGES.txt
    +    . Fixes the relogin to do relogin even if the TGT is null.
    +    (Kan Zhang via ddas)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/yahoo-merge@1079137 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/hadoop/security/UserGroupInformation.java

@@ -504,7 +504,7 @@ public class UserGroupInformation {
    * Get the Kerberos TGT
    * @return the user's TGT or null if none was found
    */
-  private KerberosTicket getTGT() {
+  private synchronized KerberosTicket getTGT() {
     Set<KerberosTicket> tickets = subject
         .getPrivateCredentials(KerberosTicket.class);
     for (KerberosTicket ticket : tickets) {
@@ -636,11 +636,8 @@ public class UserGroupInformation {
       return;
     
     KerberosTicket tgt = getTGT();
-    if (tgt == null) {
-      return;
-    }
     //Return if TGT is valid and is not going to expire soon.
-    if (System.currentTimeMillis() < getRefreshTime(tgt)) {
+    if (tgt != null && System.currentTimeMillis() < getRefreshTime(tgt)) {
       return;
     }