private ExecutorService getExecutorService() {
    if (executor == null) {
      executor = Executors.newCachedThreadPool(new ThreadFactoryBuilder()
        .setNameFormat(getClass().getSimpleName() + "-%d").setDaemon(true).build());
    }
    return executor;
  }
A procedure for migrating replication queue data from zookeeper to hbase:replication table.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/replication/MigrateReplicationQueueFromZkToTableProcedure.java