@Override
      public void run() {
        try {
          Threads.threadDumpingIsAlive(someOldThread);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
@return set of wal names present prior to split attempt.
@throws IOException if the split process fails
hbase-server/src/test/java/org/apache/hadoop/hbase/wal/TestWALSplit.java