HBASE-21050 Exclusive lock may be held by a SUCCESS state procedure f…

…orever

Signed-off-by: Michael Stack <stack@apache.org>
Signed-off-by: zhangduo <zhangduo@apache.org>

hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/Procedure.java

@@ -895,6 +895,11 @@ final void restoreLock(TEnvironment env) {
       return;
     }
 
+    if (isFinished()) {
+      LOG.debug("{} is already finished, skip acquiring lock.", this);
+      return;
+    }
+
     LOG.debug("{} held the lock before restarting, call acquireLock to restore it.", this);
     LockState state = acquireLock(env);
     assert state == LockState.LOCK_ACQUIRED;