Why Coroutines are lightweight?

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KotlinIntermediate4 min

Answer

Coroutines are lightweight because they do not map 1:1 to native OS threads.

Suspension vs Blocking: When a coroutine suspends (e.g., `delay(1000)`), it doesn't block the thread. It simply saves its state (local variables, instruction pointer) and releases the thread back to the pool.
Reuse: One thread can execute many coroutines. While one is waiting for network, the thread can execute another.
Stackless: They don't require a dedicated stack frame in the OS for each instance, unlike threads which reserve significant memory (often 1MB) just to exist.

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Want to master these concepts?

1:1 Mentorship

Builder Pattern in Kotlin?

Collections API in Kotlin?

Covariance in Kotlin?

Delay vs Thread.sleep?

Difference Between const val and val?