protected void runGenerator(int numMappers, long numNodes, String outputDir, Integer width,
      Integer wrapMultiplier, Integer numWalkers) throws Exception {
      Path outputPath = new Path(outputDir);
      UUID uuid = UUID.randomUUID(); // create a random UUID.
      Path generatorOutput = new Path(outputPath, uuid.toString());

      Generator generator = new Generator();
      generator.setConf(getConf());
      int retCode =
        generator.run(numMappers, numNodes, generatorOutput, width, wrapMultiplier, numWalkers);
      if (retCode > 0) {
        throw new RuntimeException("Generator failed with return code: " + retCode);
      }
      if (numWalkers > 0) {
        if (!generator.verify()) {
          throw new RuntimeException("Generator.verify failed");
        }
      }
      LOG.info("Generator finished with success. Total nodes=" + numNodes);
    }
Executes Generate and Verify in a loop. Data is not cleaned between runs, so each iteration
adds more data.
hbase-it/src/test/java/org/apache/hadoop/hbase/test/IntegrationTestBigLinkedList.java