private String getContainerMemDefaultMBytes() {
    Map<String, String> paramMap = _heuristicConfData.getParamMap();
    if (paramMap.containsKey(CONTAINER_MEM_DEFAULT_MB)) {
      String strValue = paramMap.get(CONTAINER_MEM_DEFAULT_MB);
      try {
        return strValue;
      }
      catch (NumberFormatException e) {
        logger.warn(CONTAINER_MEM_DEFAULT_MB + ": expected number [" + strValue + "]");
      }
    }
    return DEFAULT_MAPPER_CONTAINER_SIZE;
  }
Analyzes mapper memory allocation and requirements
app/com/linkedin/drelephant/tez/heuristics/GenericMemoryHeuristic.java