private static ThreadPoolExecutor buildReCompareExecutor(int maxThreads, Mapper.Context context) {
    if (maxThreads == 0) {
      return null;
    }

    return new ThreadPoolExecutor(0, maxThreads, 1L, TimeUnit.SECONDS, new SynchronousQueue<>(),
      buildRejectedReComparePolicy(context));
  }
Sets up the actual job.
@param conf The current configuration.
@param args The command line parameters.
@return The newly created job.
@throws java.io.IOException When setting up the job fails.
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/replication/VerifyReplication.java