@Override
    public void run() {
      try {
        internalRun();
      } catch (Throwable t) {
        caughtException.compareAndSet(null, t);
      }
    }
When we insert a higher-memstoreTS deletion of a cell but with the same timestamp, we still
need to provide consistent reads for the same scanner.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestDefaultMemStore.java