CODEWITHSUNDEEP
scalaconcurrency
matanox
matanox

Reputation: 13686

Scala futures and threads

Reading the scala source code for scala.concurrent.Future and scala.concurrent.impl.Future, it seems that every future composition via map dispatches a new task for an executor. I assume this commonly triggers a context switch for the current thread, and/or an assignment of a thread for the job.

Considering that function flows need to pass around Futures between them to act on results of Futures without blocking (or without delving into callback spaghetti), isn't this "reactive" paradigm very pricy in practice, when code is well written in a modular way where each function only does something small and passes along to other ones?

Upvotes: 6

Views: 539

Answers (1)

Gamlor
Gamlor

Reputation: 13238

It depends on the execution context. So you can choose the strategy.

You're executor can also just do it in the calling thread, keeping the map-calls on the same thread. You can pass your own strategy by passing explicitly the execution context or use the implicit.

I would first test what the default fork/join pool does, by logging which thread was used. Afaik newer versions of it sometimes utilize the submitting thread. However, I don't know if that's used / applied for scala future callbacks.

Upvotes: 2

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