Operators running on the main thread by default.

[SarthakM9]

Consider this code:

RxTextView.afterTextChangeEvents(editText)
        .subscribeOn(Schedulers.io())
        .skip(1)
        .map({ input ->
            Log.i("MAPPING ON:", Thread.currentThread().name)
            // some code
        })
        .debounce(2, TimeUnit.SECONDS)
        .subscribe {
            Log.i("SUBSCRIBED ON:", Thread.currentThread().name)
            // some code
        }

and this is the log that gets printed:

I/MAPPING ON:: main
I/SUBSCRIBED ON:: RxComputationThreadPool-1

Why is map operator being called on main thread? Shouldn't the map operator and subscribe function be called on IO thread? Where is Computation thread coming from?

And, if I add observeOn(Schedulers.io()) just below subscribeOn():

I/MAPPING ON:: RxCachedThreadScheduler-3
I/SUBSCRIBED ON:: RxComputationThreadPool-1

now map operator gets called on IO thread but subscribe is still getting called on Computation thread.

I would happily move this question to SO if it is just my misunderstanding and not an issue.

Versions I am using: rx_java = '2.0.7' rx_android = '2.0.1' rx_binding_kotlin = '2.0.0'

[artem-zinnatullin]

SubscribeOn controls the subscription thread, but does not control the emission thread.

In your case you subscribe on io, you should not do that because Android Framework expects you to work with Views on the threads they were created on (main in your case). And it's not going to prevent afterTextChange events from emitting on main thread, RxJava has observeOn for that.

Computation thread comes from Computation scheduler used as a default scheduler by debounce operator.

This is not a bug and it's not directly related to RxAndroid.

On Tue, Aug 22, 2017, 1:22 AM Sarthak Mittal notifications@github.com wrote:

Consider this code:

RxTextView.afterTextChangeEvents(editText) .subscribeOn(Schedulers.io()) .skip(1) .map({ input -> Log.i("MAPPING ON:", Thread.currentThread().name) // some code }) .debounce(2, TimeUnit.SECONDS) .subscribe { Log.i("SUBSCRIBED ON:", Thread.currentThread().name) // some code }

and this is the log that gets printed:

I/MAPPING ON:: main I/SUBSCRIBED ON:: RxComputationThreadPool-1

Why is map operator being called on main thread? Shouldn't the map operator and subscribe function be called on IO thread? Where is Computation thread coming from?

And, if I add observeOn(Schedulers.io()) just below subscribeOn():

I/MAPPING ON:: RxCachedThreadScheduler-3 I/SUBSCRIBED ON:: RxComputationThreadPool-1

now map operator gets called on IO thread but subscribe is still getting called on Computation thread.

I would happily move this question to SO if it is just my misunderstanding and not an issue.

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[SarthakM9]

@artem-zinnatullin thanks for your time!

I am not doing any UI related operation inside map or inside subscribe. I would like to run both of them on IO thread as I am performing network operation in both. So, If I understand it right, I should do it like this:

RxTextView.afterTextChangeEvents(editText)
        .observeOn(Schedulers.io())
        .skip(1)
        .map()
        .debounce(2, TimeUnit.SECONDS)
        .observeOn(Schedulers.io())
        .subscribe {
            // whatever
        }

is this implementation correct?

[JakeWharton]

Pass the scheduler on which you want notifications in the subscribe lambda as the third argument to debouce. By default it's Schedulers.computation().

[JakeWharton]

Closing since this isn't an RxAndroid or RxJava issue but a usage question. Please consider using StackOverflow or the RxJava mailing list for questions in the future.

[SarthakM9]

@JakeWharton Yes, will use SO. Thanks! :)