Bundles are currently completely up to the runner, and different runners do them differently. In addition to Flink, the Dataflow runner creates smallish bundles when run in streaming mode, as the streaming-mode runner is optimizing for latency (so a bundle might be small simply because not enough time has passed to make it large). Bundles being large is usually less of an issue - you simply need to occasionally commit in processElement if the bundle being built up is too large.
However there is a simple workaround. You can GBK on a fixed number of shard keys and set a elementCountAtLeast trigger to trigger when enough data has arrived. Reuven On Wed, Nov 15, 2017 at 4:38 PM, Romain Manni-Bucau <rmannibu...@gmail.com> wrote: > Hi guys, > > The subject is a bit provocative but the topic is real and coming > again and again with the beam usage: how a dofn can handle some > "chunking". > > The need is to be able to commit each N records but with N not too big. > > The natural API for that in beam is the bundle one but bundles are not > reliable since they can be very small (flink) - we can say it is "ok" > even if it has some perf impacts - or too big (spark does full size / > #workers). > > The workaround is what we see in the ES I/O: a maxSize which does an > eager flush. The issue is that then the checkpoint is not respected > and you can process multiple times the same records. > > Any plan to make this API reliable and controllable from a beam point > of view (at least in a max manner)? > > Thanks, > Romain Manni-Bucau > @rmannibucau | Blog | Old Blog | Github | LinkedIn >
