protected void addUpdaterThreads(int numThreads) throws IOException {
    for (int i = 0; i < numThreads; ++i) {
      HBaseUpdaterThread updater = new HBaseUpdaterThread(i);
      updaters.add(updater);
    }
  }
Use batch vs. separate updates for every column in a row
hbase-diagnostics/src/main/java/org/apache/hadoop/hbase/util/MultiThreadedUpdater.java