@Override
  public void handleInputInitializerEvent(List<InputInitializerEvent> events) throws Exception {
    for (InputInitializerEvent e : events) {
      pruner.addEvent(e);
    }
  }
SplitSerializer is a helper class for taking care of serializing splits to the tez scratch dir
when a size criteria defined by "hive.tez.input.fs.serialization.threshold" is met.
It utilizes an ExecutorService for parallel writes to prevent a single split write operation
becoming the bottleneck (as write() is called from a loop currently).
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/HiveSplitGenerator.java