apache/spark — pull request #149 by rxin (2014-03-15 08:10:54+00:00)
Title: SPARK-1255: Allow user to pass Serializer object instead of class name for shuffle.

This is more general than simply passing a string name and leaves more room for performance optimizations.

Note that this is technically an API breaking change - but I suspect nobody else in this world has used this API other than me in GraphX and Shark.