How do you know wether you use Dispatchers.Default on Android side? In terms of mapping objects? If ...

# coroutines

[Pablo]

How do you know wether you use Dispatchers.Default on Android side? In terms of mapping objects? If it's a 1:1 mapper is it really needed to use withContext(Dispatchers.Default)? I thought that it's needed when you need to do heavy operations like sorting, etc..?

[Marko Novakovic]

Dispatchers.Default is really tricky one. Use it with caution. You should Dispatchers.Default handle the same number of operations as number of cores on the device. If you have more you will wait for one of them to finish in order to do another one. On low spec devices that could be only 2 operations. You shouldn’t really have problems here but just keep this in mind

[Marko Novakovic]

If you start running into problems it’s better to implement your own unbound Dispatcher than to use Dispatchers.Default

[Marko Novakovic]

Also single thread dispatcher is more than enough for most apps. I don’t know how heavy is the sorting you need to do, if that’s not just an example, but it should work

[Pablo]

Nono, mine it's not hard but I'm wondering if someday I need to do a super heavy sorting, and stuff like requieres a lot of CPU then I'd use Dispatchers.Default?

[Pablo]

When you talk about a single thread dispatcher what do you mean?

[Marko Novakovic]

you can read this post for more information
https://www.techyourchance.com/coroutines-dispatchers-default-and-dispatchers-io-considered-harmful/

[Marko Novakovic]

and here is single thread one
https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/new-single-thread-context.html

[Marko Novakovic]

your dispatcher will use a single thread. <http://Dispatcher.IO|Dispatcher.IO> for example, same for Dispatcher.Default, can start coroutine one one thread and finish it on some other thread. this dispatcher use just one thread