Kryo #12
Description
Spark recommends Kryo serialization.
This issue tracks tasks to ensure that this serialization framework is used and works correctly.
- find and fix cases where generated RDD are not using Kryo (e.g. MEMORY_ONLY)
- implement built-in Kryo serialization to take advantage of the bitfields information that stores which fields are populated
- write and perform benchmark tests to check if it's really better