Suspending vs Blocking in Kotlin Coroutines? - Android Interview Questions | Android Engineers

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KotlinIntermediate4 min

Suspending vs Blocking in Kotlin Coroutines?

Answer

Blocking

Blocks the Thread: The thread sits idle, waiting for the operation to finish. It cannot do anything else.
Impact: If this happens on the Main Thread, the app freezes (ANR).

Suspending

Frees the Thread: The function pauses execution but returns the thread to the pool.
Impact: The thread is free to update the UI or run other coroutines while the operation (like a network call) completes in the background.
Mechanism: Uses the `suspend` keyword and state machines.

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