public int run(Path outputDir, int numReducers) throws Exception {
      LOG.info("Running Verify with outputDir=" + outputDir + ", numReducers=" + numReducers);

      job = Job.getInstance(getConf());

      job.setJobName("Link Verifier");
      job.setNumReduceTasks(numReducers);
      job.setJarByClass(getClass());

      setJobScannerConf(job);

      Scan scan = new Scan();
      scan.addColumn(FAMILY_NAME, COLUMN_PREV);
      scan.setCaching(10000);
      scan.setCacheBlocks(false);
      if (isMultiUnevenColumnFamilies(getConf())) {
        scan.addColumn(BIG_FAMILY_NAME, BIG_FAMILY_NAME);
        scan.addColumn(TINY_FAMILY_NAME, TINY_FAMILY_NAME);
      }

      TableMapReduceUtil.initTableMapperJob(getTableName(getConf()).getName(), scan,
        VerifyMapper.class, BytesWritable.class, BytesWritable.class, job);
      TableMapReduceUtil.addDependencyJarsForClasses(job.getConfiguration(),
        AbstractHBaseTool.class);

      job.getConfiguration().setBoolean("mapreduce.map.speculative", false);

      job.setReducerClass(VerifyReducer.class);
      job.setOutputFormatClass(SequenceFileAsBinaryOutputFormat.class);
      job.setOutputKeyClass(BytesWritable.class);
      job.setOutputValueClass(BytesWritable.class);
      TextOutputFormat.setOutputPath(job, outputDir);

      boolean success = job.waitForCompletion(true);

      if (success) {
        Counters counters = job.getCounters();
        if (null == counters) {
          LOG.warn("Counters were null, cannot verify Job completion."
            + " This is commonly a result of insufficient YARN configuration.");
          // We don't have access to the counters to know if we have "bad" counts
          return 0;
        }

        // If we find no unexpected values, the job didn't outright fail
        if (verifyUnexpectedValues(counters)) {
          // We didn't check referenced+unreferenced counts, leave that to visual inspection
          return 0;
        }
      }

      // We failed
      return 1;
    }
Dump out extra info around references if there are any. Helps debugging.
@return StringBuilder filled with references if any.
hbase-it/src/test/java/org/apache/hadoop/hbase/test/IntegrationTestBigLinkedList.java