What is viewModelScope?

An Android KTX scope tied to a ViewModel lifecycle. It cancels coroutines automatically when the ViewModel is destroyed.

When use supervisorScope?

When one child failure should not cancel siblings — useful for independent parallel tasks.

Intermediate 8 min readKotlin 2.0

Kotlin Coroutine Scope — Structured Concurrency

A coroutine scope defines the lifetime of coroutines. Structured concurrency means children belong to a parent and are cancelled together.

What You Will Learn

Define parent-child coroutine relationships
Use coroutineScope { } to wait for children
Understand cancellation propagation
Compare coroutineScope vs supervisorScope
Relate scopes to Android viewModelScope

Structured Concurrency

Every coroutine has a parent. When the parent is cancelled, children are cancelled too. This prevents leaked work when a screen closes or a request times out.

coroutineScope Waits for Children

kotlin
import kotlinx.coroutines.*

fun main() = runBlocking {
    coroutineScope {
        launch { delay(200); println("Child A") }
        launch { delay(100); println("Child B") }
    }
    println("Scope finished")
}

Output

Child B Child A Scope finished

coroutineScope suspends until all children complete. B finishes before A because of shorter delay.

Dependency required: implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.9.0")

Cancellation Propagation

Cancelling a scope cancels every child launched inside it. This is how viewModelScope stops work when a ViewModel is cleared.

Cancel a Scope

kotlin
import kotlinx.coroutines.*

fun main() = runBlocking {
    val scope = CoroutineScope(Dispatchers.Default)
    scope.launch { delay(500); println("Should not print") }
    delay(50)
    scope.cancel()
    delay(600)
    println("Done")
}

Output

Done

scope.cancel() stops the child before it can print. Only "Done" appears.

Practice Exercise

Exercisemultiple choice

What happens when a parent coroutine scope is cancelled?

Quick Quiz

What does coroutineScope { } do?

Kotlin Coroutine Scope — Structured Concurrency

What You Will Learn

Structured Concurrency

coroutineScope Waits for Children

Cancellation Propagation

Cancel a Scope

Practice Exercise

Quick Quiz

Frequently Asked Questions

Related Tutorials