ShuffleBlockResolver

ShuffleBlockResolver is an abstraction of shuffle block resolvers that BlockManager uses to retrieve a shuffle block data for a logical shuffle block identifier (i.e. map, reduce, and shuffle).

Shuffle block data files are often referred to as map outputs files.
IndexShuffleBlockResolver is the default and only known ShuffleBlockResolver in Apache Spark.
Table 1. ShuffleBlockResolver Contract
Method Description

getBlockData

getBlockData(
  blockId: ShuffleBlockId): ManagedBuffer

Retrieves the data (as a ManagedBuffer) for the given block (a tuple of shuffleId, mapId and reduceId).

Used when BlockManager is requested to retrieve a block data from a local block manager and block data

stop

stop(): Unit

Stops the ShuffleBlockResolver

Used when SortShuffleManager is requested to stop