No More Callbacks: 10,000 Actors, 10,000 Threads, 10,000 Spaceships

Re:No More Callbacks: 10,000 Actors, 10,000 Threads, 10,000 ... by hp on Thursday October 17, 2013 @07:47AM (#6564727)

Scala has an `async`/`await` feature (like C#) now, which hides the Future ceremony and gives sequential syntax. https://github.com/scala/async

I guess this does still require the `await` word, but I think it's good to have a magic word for "suspend execution now" so you can see where it's happening.

An OS thread still has to block on blocking IO calls somewhere, of course. There's no "syntactic" fix for that on the JVM - you have to actually port the blocking IO to nonblocking IO - AFAIK nobody can magically fix JDBC to be nonblocking from outside JDBC.

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Re:No More Callbacks: 10,000 Actors, 10,000 Threads, 10,000 ... by pron on Thursday October 17, 2013 @07:50AM (#6564744)

Essentially, Quasar provides async and await for all JVM languages. async is called `Fiber.start()`, and await is called `Fiber.park`.

Other than working for all JVM languages, Quasar fibers are more general in that they can spawn many functions (they have a stack), while async is limited to a single expression block. Because of this, we can hide the "await" deep inside the JDBC call stack.

Under the hood, they are similar: both instrument your code. Only async does this at the language level (it's a Scala macro), while fibers do it at the bytecode level.

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