[akka-streams] How to guarantee parallel execution of Sunflower?

[Alexey Shuksto]

Hello there,

Is there a way to guarantee that subflows after '.groupBy(..)' operation would be performed in parallel (I.e. by separate actors) until merged back into Flow?

For example, in code like 'Flow[Int].groupBy(3,_ % 3).map(_.toString).mergeSubstreams()' where should I put something like async barrier?

I've tried it after groupBy and after map, but according to logs it is still executed in the same dispatcher thread.

Scala 2.12.3, Akka 2.5.3.

[Patrik Nordwall]

It should work with .async after groupBy. It can still be same thread. To see it (different threads) you might have to add a sleep in the map.

/Patrik

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[Alexey Shuksto]

Thanks, Patrick!

One more question regarding'.async' -- is there any point in adding it to Merge/BroadcastHub stages or their materialized sinks/sources?

[Patrik Nordwall]

MergeHub, BroadcastHub and PartitionHub always add an asynchronous boundary so you shouldn't use .async with them.

/Patrik

On Sun, Aug 13, 2017 at 8:35 PM, Alexey Shuksto <sei...@gmail.com> wrote:

Thanks, Patrick!

One more question regarding'.async' -- is there any point in adding it to Merge/BroadcastHub stages or their materialized sinks/sources?

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>>>>>>>>>>      Read the docs: http://akka.io/docs/
>>>>>>>>>>      Check the FAQ: http://doc.akka.io/docs/akka/current/additional/faq.html
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Patrik Nordwall
Akka Tech Lead
Lightbend -  Reactive apps on the JVM
Twitter: @patriknw