protected void setBalancer(boolean onOrOff, boolean synchronous) throws Exception {
    Admin admin = this.context.getHBaseIntegrationTestingUtility().getAdmin();
    try {
      admin.balancerSwitch(onOrOff, synchronous);
    } catch (Exception e) {
      getLogger().warn("Got exception while switching balance ", e);
    }
  }
Returns current region servers - active master
hbase-it/src/test/java/org/apache/hadoop/hbase/chaos/actions/Action.java