I wanted to get a customized <Dispatchers.IO> with custom number of threads, is it ok and wise to us...

# coroutines

[coder82]

I wanted to get a customized Dispatchers.IO with custom number of threads, is it ok and wise to use
ExperimentalCoroutineDispatcher().blocking(nThreads) ?
@gildor

[withoutclass]

Just create a fixed thread pool and then use it as as displatcher

[withoutclass]

Executors.newFixedThreadPool(5).toCoroutineDispatcher() IIRC

[coder82]

but that is not optimized for IO isn't it?

[withoutclass]

The IO dispatcher is just a shared pool of threads that get spin up on demand, it shares it's threads with the default dispatcher. So, if you just want a pool of some small number of threads to do work on, the example I posted would be fine

[withoutclass]

The downside would be that I don't think the fixed thread pool would shutdown/spin up threads on demand but I could be wrong

[louiscad]

You can also configure the upper limit of <http://Dispatchers.IO|Dispatchers.IO> which defaults to 64, it's documented.

[coder82]

yes I saw that but I wanted to create a parametrized factory to do it so didn't want to deal with properties

[withoutclass]

Problem with the configuration is it would effect all uses of default/IO dispatcher, but maybe not a problem for this case

[coder82]

as well...

[coder82]

do you have an idea on how to know how many elements are in a channel at any given moment? I tried count() but it consumes them

[coder82]

in order to count them I might have to just consume them and push them back in

[withoutclass]

yea it always pulls them all when you count

[withoutclass]

if you need to know how many there are channels may not be what you want

[coder82]

uhm, right why not using a deque for example

[coder82]

i just wanted to know if it's full or not to assess how loaded is the worker pool pulling messages from the channel

[coder82]

so i need a concurrent data structure

[coder82]

but maybe there is another way to do what i want to do

[coder82]

basically i want to measure how busy is a worker pool

[coder82]

uhm maybe i could use an atomic counter

[coder82]

when i submit the operation to the pool

[coder82]

measuring how full the channel is doesn't anyway tell me much other than "at least 1 thread free" or "all busy"

[Dico]

You can use a limiting dispatcher.
This is internal coroutines api.
You need to cast either default or io dispatcher, I dont remember

(<http://Dispatchers.IO|Dispatchers.IO> as SomeInternalDispatcherType).limitingDispatcher(n)

[Dico]

I think default dispatcher is just limiting dispatcher from Io but not certain, been some time since I looked at it

[gildor]

I wanted to get a customized Dispatchers.IO with custom number of threads, is it ok and wise to use

It really depends on your case