private void startRegionServer() throws Exception {
    rs = cluster.addRegionServer();
    rs.start();

    for (int i = 0; i * SLEEP_INTERVAL < SLEEP_TIME; i++) {
      // we cannot block on wait for rs at this point , since master is not up.
      Thread.sleep(SLEEP_INTERVAL);
      assertTrue(rs.isAlive());
    }
  }
Tests the boot order indifference between regionserver and master
hbase-server/src/test/java/org/apache/hadoop/hbase/TestClusterBootOrder.java