src/share/classes/java/util/concurrent/locks/AbstractOwnableSynchronizer.java

*** 62,78 ****
--- 62,86 ----
       * The current owner of exclusive mode synchronization.
       */
      private transient Thread exclusiveOwnerThread;
  
      /**
+      * The current or last owner of exclusive mode synchronization.
+      */
+     private transient Thread lastExclusiveOwnerThread;
+ 
+     /**
       * Sets the thread that currently owns exclusive access.
       * A {@code null} argument indicates that no thread owns access.
       * This method does not otherwise impose any synchronization or
       * {@code volatile} field accesses.
       * @param thread the owner thread
       */
      protected final void setExclusiveOwnerThread(Thread thread) {
+         if (thread != null) {
+                 lastExclusiveOwnerThread = thread;
+         }
          exclusiveOwnerThread = thread;
      }
  
      /**
       * Returns the thread last set by {@code setExclusiveOwnerThread},