slouc/concurrency-in-scala-with-ce

Introduction to concepts of asynchronous and concurrent programming in Scala, based on the Cats Effect library.

concurrency-in-scala-with-ce's Issues

How a fiber's non blocking behaviour is implemented?

The section in which is given the definition of a Fiber says that

Also, blocking a fiber doesn't block the underlying thread.

Since in text there isn't an explanation for this behaviour I think that would be great to add it. I'd submit a PR but unfortunately I haven't yet understood how it's possible to implement such a behaviour 😅.

Threadpool queues

Hi, how are you, I was reading this part, and I think it might be missing some information about the thread pool queue

"Blocking asynchronous operations:

Unbounded cached pool. Unbounded because blocking operation can (and will) block a thread for some time, and we want to be able to serve other I/O requests in the meantime. Cached because we could run out of memory by creating too many threads, so it’s important to reuse existing threads."

You can also get out of memory if you use an unbounded tasks queue in the threadpool. If all the cached threads are in use, your queue might go up and your app go down. my 2 cents

Run Loop

Hi, I really really love your write-up. I just have a small question.

Since a for-comprehension is a series of nested flatMaps where the computation is sequenced, and the result of a previous computation is used to get the next computation. Shouldn't the Run loop here be:

FlatMap(
    Delay(() => println("What's up?")),
    (_: Unit) => FlatMap(
      Delay(() => readLine),
      (input: String) => Delay(() => println(s"Ah, $input is up!"))
    )
  )

where the function k is what leads to the next FlatMap ?

Using a toy interpreter, funny enough, I can't seem to see any difference between the two.

Minor clarification

In the shift example you wrote

Code is pretty straightforward - we have a recursive loop that goes on forever, and all it does is print out some ID ("A" or "B").

On my reading and executing this, the first example with def loop prints "A" continually. (I commented out the 'shift' to match your example).

Parallelism or parallel execution?

Hey 🤗,

I am a bit newer about concurrency and parallelism and I would like to make an open question. Which is the different between parallel execution and parallelism in the docs? Reading the repository I don't really know if we are threatening the concept like one. There is any specific example I can check to visualise how a task is subdivided in subtask and paralleled?

Thank you! 🙂