Hi , I want to force ANR trigger in my app. Base o...

# android

[Jason]

Hi , I want to force ANR trigger in my app. Base on ANR trigger concept
https://developer.android.com/topic/performance/vitals/anr
I use below code to reproduce

viewModelScope.launch(Dispatchers.Main) {
            while (true) {}
        }

OR

viewModelScope.launch(Dispatchers.Main) {
   delay(TimeUnit.SECONDS.toMillis(5))
}

But UI is stuck but ANR does not occur … Any help?

[Kohei Moroi]

Hi, you can reproduce ANR with coroutine like below:

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        findViewById<TextView>(R.id.text_button).setOnClickListener {
            GlobalScope.launch(Dispatchers.Main) {
                while (true) {

                }
            }
        }
    }

When nothing else happens on the main thread, you will not see an ANR pop up immediately. You can trigger it by pressing the button and wait a few seconds.

[Jason]

@Kohei Moroi
Thank for reply. Actually, I have tried above code but the dialog still does not show .
Basically, I have a simple screen with 2 button. Button A calls forceANR() function, Button B is a normal button just log something such as “click button B”.
So, when I click on button A, the screen is stuck. It is blocked that I can not click on button B.
What’s problem here ?

fun forceANRError() {
    GlobalScope.launch(Dispatchers.Main) {
        while (true) {
        }
    }
}

fun onClickButtonA() { forceANRError() }
fun onClickButtonB() { Log.d("Click Button B") }

[Jason]

Ah, I solved my problem !

[Aslam Hossin]

@Jason
I have inspired more in your replayed than answered above. Thanks for your inspiring thoughts.