apache/spark — pull request #2830 by davies (2014-10-16 19:44:13+00:00)
Title: [SPARK-3971] [MLLib] [PySpark] hotfix: Customized pickler should work in cluster mode

Customized pickler should be registered before unpickling, but in executor, there is no way to register the picklers before run the tasks.

So, we need to register the picklers in the tasks itself, duplicate the javaToPython() and pythonToJava() in MLlib, call SerDe.initialize() before pickling or unpickling.