I wanted to reach out that I will be continuing from where Eugene left off with SplittableDoFn. I know that many of you have done a bunch of work with IOs and/or runner integration for SplittableDoFn and would appreciate your help in advancing this awesome idea. If you have questions or things you want to get reviewed related to SplittableDoFn, feel free to send them my way or include me on anything SplittableDoFn related.
I was part of several discussions with Eugene and I think the biggest outstanding design portion is to figure out how dynamic work rebalancing would play out with the portability APIs. This includes reporting of progress from within a bundle. I know that Eugene had shared some documents in this regard but the position / split models didn't work too cleanly in a unified sense for bounded and unbounded SplittableDoFns. It will likely take me awhile to gather my thoughts but could use your expertise as to how compatible these ideas are with respect to to IOs and runners Flink/Spark/Dataflow/Samza/Apex/... and obviously help during implementation.
