Coroutines delay and Future get

Main.kt

import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Job
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import java.util.concurrent.CompletableFuture

fun main() {
    val future = CompletableFuture<Unit>()

    doSuspend {
        println("called")
        future.complete(Unit)
    }

    future.get()
    println("complete")
}

fun doSuspend(callback: () -> Unit) {
    CoroutineScope(Job()).launch {
        println("call callback in 100ms")
        delay(100)
        println("call callback now")
        callback()
    }
}

MainActivity.kt

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Job
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import java.util.concurrent.CompletableFuture

class MainActivity : AppCompatActivity() {
    companion object {
        private const val TAG = "MainActivity"
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val future = CompletableFuture<Unit>()

        doSuspend {
            Log.d(TAG, "called")
            future.complete(Unit)
        }

        future.get()
        Log.d(TAG, "complete")
    }

    private fun doSuspend(callback: () -> Unit) {
        CoroutineScope(Job()).launch {
            Log.d(TAG, "call callback in 100ms")
            delay(100)
            Log.d(TAG, "call callback now")
            callback()
        }
    }
}

In Android code (MainActivity.kt), when doSuspend with future will block forever when get() is called. Particularly, inside doSuspend function, delay suspend function never completes.

Meanwhile, on generic JVM environment, the same code can stop.

This issue looks specific to coroutines v1.6.0. It's not reproduced with v1.5.3. Also this issue might be related the bug in 1.6.0 which could be fixed by this PR.

Kotlin/kotlinx.coroutines#3131