Is it possible to set the default dispatcher to Dispatches M

Question

Is it possible to set the default dispatcher to Dispatches Main I almost never want the default dispatcher and like to run my launch always on the main dispatcher and only switch the context when necessary

Dico · Answer

For GlobalScope

Paul Woitaschek · Answer

No the `Dispatchers default`

dekans · Answer

Default dispatcher is defined by the scope you use

Paul Woitaschek · Answer

I don t think so

Paul Woitaschek · Answer

``` The default CoroutineDispatcher that is used by all standard builders like launch CoroutineScope launch async CoroutineScope async etc if no dispatcher nor any other ContinuationInterceptor is specified in their context It is backed by a shared pool of threads on JVM By default the maximal level of parallelism used by this dispatcher is equal to the number of CPU cores but is at least two Level of parallelism X guarantees that no more than X tasks can be executed in this dispatcher in parallel JvmStatic public actual val Default CoroutineDispatcher = createDefaultDispatcher ```

dekans · Answer

`val scope = MainScope ` `scope launch runsInMainThread ` Because scope dispatcher is Dispatchers Main

Paul Woitaschek · Answer

I don t get what you re saying

dekans · Answer

cf gt if no dispatcher nor any other ContinuationInterceptor is specified in their context

dekans · Answer

If your scope specifies a dispatcher this is the default one used by `launch` if none specified in parameters

Dico · Answer

Can you share a code snippet where you are explicitly using Dispatchers Main

Dico · Answer

What Geoffrey is saying is exactly right

Paul Woitaschek · Answer

Still don t get it I don t have a snippet I think that the default of `Dispatchers Default` not being `Dispatchers Main` is not right

Adam Powell · Answer

you should never run into this being a problem because any `CoroutineScope` you launch into should have a dispatcher configured already You should be creating scopes through standardized utilities so that you never have to think about it e g `LifecycleOwner lifecycleScope` `ViewModel viewModelScope` or similar definitions you write yourself

Adam Powell · Answer

If you find yourself regularly creating one off scopes by hand to launch into you re probably not getting the full benefits of structured concurrency

Adam Powell · Answer

`Dispatchers Main` would make a poor default anyway it would be an unnecessarily UI centric perspective for a general tool like coroutines to adopt

Adam Powell · Answer

and even if you did manage to set `Dispatchers Default` to point at `Dispatchers Main` for your app it would probably have catastrophic effects on the behavior of libraries you use that assume `Dispatchers Default` is a pool of worker threads for CPU bound work Those libraries would start blocking your main thread very quickly if you changed that assumption out from under them slightly smiling face

dekans · Answer

And maybe all platform don t have a main dispatcher kotlinx is multiplatform ready

Paul Woitaschek · Answer

Thanks for the interesting insights totally makes sense