extra data movement with multi-worker batching

[kleinschmidt]

@ericphanson noted in beacon-biosignals/OldOndaBatches.jl#18 that there's some apparently extraneous data movement in multi-worker batching: #18 (comment)

so here the "batch manager" (the process with the Batcher) fetch the future from the worker, and puts it on channel which is a remote channel to somewhere else (the trainer, I guess?). I wonder if that's extra data movement we don't strictly need

I guess we kinda do need it, bc if we just passed the remote channel on to the workers, they wouldn't know what order to do stuff in, and passing it through the batch manager let's us straighten out the order before loading up the remote channel.

This may or may not turn out to be an issue. One way around it would be to remotecall the put! to have it execute on the batch worker.