a) If one or more tasks for a stage (and so its shuffle id) is going to be recomputed, if it is an INDETERMINATE stage, all shuffle output will be discarded and it will be entirely recomputed (see here <https://github.com/apache/spark/blob/3e2470de7ea8b97dcdd8875ef25f044998fb7588/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala#L1477> ).
If a reducer (in a downstream stage) fails to read data, can we find out which tasks should recompute their output? From the previous discussion, I thought this was hard (in the current implementation), and we should re-execute all tasks in the upstream stage.
Thanks, --- Sungwoo
