@Before
  public void before() throws IOException {
    LOG.info("before");
    UTIL.ensureSomeRegionServersAvailable(1);
    LOG.info("before done");
  }
Spark creates many instances of TableOutputFormat within a single process. We need to make sure
we can have many instances and not leak connections. This test creates a few TableOutputFormats
and shouldn't fail due to ZK connection exhaustion.
hbase-mapreduce/src/test/java/org/apache/hadoop/hbase/mapred/TestTableOutputFormatConnectionExhaust.java