private void waitForClusterOnline() {
    while (true) {
      if (master.getMaster().isInitialized()) {
        break;
      }
      try {
        Thread.sleep(100);
      } catch (InterruptedException ignored) {
        // Keep waiting
      }
    }
    rs.waitForServerOnline();
  }
Tests the boot order indifference between regionserver and master
hbase-server/src/test/java/org/apache/hadoop/hbase/TestClusterBootOrder.java