static void splitPlan(ReduceSinkOperator cRS,
      Task<?> parentTask, Task<?> childTask,
      GenMRProcContext opProcCtx) throws SemanticException {
    assert parentTask != null && childTask != null;
    splitTasks(cRS, parentTask, childTask, opProcCtx);
  }
Met cRS in pRS(parentTask)-cRS-OP(childTask) case
Split and link two tasks by temporary file : pRS-FS / TS-cRS-OP
ql/src/java/org/apache/hadoop/hive/ql/optimizer/GenMapRedUtils.java