isolates

A Dart Isolates example (Actors in Dart)

Dart Isolates give you a way to perform real multi-threading in Dart applications, the ability to truly run code on another thread. (For more information on that statement, see Dart futures are NOT run in a separate thread.)

When I first read that Isolates were like actors I was very interested in them, but then I was surprised to see that (IMHO) they are implemented in a more low-level/primitive way than something like the Akka Actors library. (The entrepreneur out there might see this as an opportunity to create an Akka-like port for Dart and Flutter.)

Dart futures are NOT run in a separate thread (they are run in the event loop) alvin September 26, 2019 - 11:04am

I’ve been working with Flutter and Dart for several weeks now, and I was surprised to read several times that Dart is single-threaded, knowing that it has a concept of a Future (or futures) and async methods. Last night I read this excellent article about Dart’s event loop, which sums up Dart futures very nicely in that statement:

“the code of these Futures will be run as soon as the Event Loop has some time. This will give the user the feeling that things are being processed in parallel (while we now know it is not the case).”

Earlier in the article the author also states:

“An async method is NOT executed in parallel but following the regular sequence of events, handled by the Event Loop, too.”

So, in summary, Dart has a single-threaded event loop, and futures and async methods aren’t handled by a separate thread; they’re handled by the single-threaded event loop whenever it has nothing else to do.

I just wanted to note this here for myself today, but for many more details, please see that article, which also discusses Dart isolates, which are like a more primitive form of Akka actors.