@After
  public void tearDown() throws Exception {
    UTIL.shutdownMiniCluster();
  }
This testcase is used to ensure that the compaction marker will fail a compaction if the RS is
already dead. It can not eliminate FNFE when scanning but it does reduce the possibility a lot.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompactionInDeadRegionServer.java