SerializedShuffleHandle is a ShuffleHandle to identify the choice of a serialized shuffle.
SerializedShuffleHandle is used to create an UnsafeShuffleWriter.
SerializedShuffleHandle takes the following to be created:
- [[shuffleId]] Shuffle ID
- [[numMaps]] Number of mappers
- [[dependency]] ShuffleDependency[K, V, V]
SerializedShuffleHandle is created when
SortShuffleManager is requested for a ShuffleHandle (for a ShuffleDependency).
SortShuffleManager determines what shuffle handle to use by first checking out the requirements of BypassMergeSortShuffleHandle before SerializedShuffleHandle's.