Bentoml: Support distributed batch inferencing job on Apache Spark cluster

[parano]

Proposal WIP

[Talador12]

Is this related to https://github.com/bentoml/BentoML/issues/666 and https://github.com/bentoml/BentoML/pull/957 ?

[parano]

@Talador12 sorry I haven't got a chance to fill in the issue description yet. This one is very different from #666 and #957. This ticket is about applying ML model packaged with BentoML to large data set on a Spark cluster. It should work for models trained with any of the ML frameworks that BentoML supports(e.g. Tensorflow, Scikit-learn etc). While #666 is about support serving Spark MLlib model in BentoML.

Note that users can already do this with BentoML & spark today. Although we want to provide a set of tools on top of the existing BentoML input adapters API to make working with Spark's data types more easily.

[xuzikun2003]

I would like to pick up this work and here is the design doc
https://docs.google.com/document/d/1C7_BT1kIF8Z2YJXioPUSg5J0yfDEfN5g5zYtcZW2Nx8/edit?usp=sharing