Changed tutorial so consumers are not overwhelmed by producers #3762
Conversation
| ```scala mdoc:compile-only | ||
| import cats.effect._ | ||
| import cats.effect.std.Console | ||
| import cats.syntax.all._ | ||
| import collection.immutable.Queue | ||
| import scala.collection.immutable.Queue | ||
|
|
||
| def producer[F[_]: Sync: Console](queueR: Ref[F, Queue[Int]], counter: Int): F[Unit] = |
There was a problem hiding this comment.
Sync seems unnecessarily strong here.
There was a problem hiding this comment.
It's not strictly required, that is true, we could just use cats.Monad. But I preferred to use CE type classes, as in the other code snippets that use Sync and Async. I'm ok with changing it but please let's be certain that is what we want 🙂 (implies changes in snippets, text and linked repo).
There was a problem hiding this comment.
While a decision is taken about this I have addressed the other comments, thanks for the input!
There was a problem hiding this comment.
I definitely think Sync/Async is too much here. But since it's already there, I don't think there is any need to change them in this PR. It's fine to leave it for a followup.
The second section of the tutorial describes how to use fibers to solve the producer-consumer problem. Thing is, as the code is now, producers outpace consumers so much that consumers seem to be 'frozen'. The explication seems to be the
Ref.modifyrun by consumers is way slower than theRef.getAndUpdatecall run by producers. This forces consumers to retry once and again to run themodifycall.This PR is to add text at the end of the first subsection (the one introducing a 'naive' solution to the producers-consumers problem) to describe the problem and to propose several solutions: using a
.sleepcall (the one used in the code samples); usingAtomicCellinstead ofRef, or using a bounded queue (which is implemented in another section afterwards).The new version of the tutorial can be read online here. All code samples are available here.
Other minor changes:
transferandtransmitfunctions in a single onetransferin order to simplify code and ease understandingSync[F].whenAinstead ofif ... else Sync[F].unitcatseffecttutorial.CopyFileto correct onecatseffecttutorial.copyfile.CopyFile