Why is there code that is executed when the thread is blocked using coroutines?

Question

Why does it print 'a' after 1 second if the thread is blocked for 3 seconds?

When a thread is blocked it can't do any computation until it is unlocked. How come is it possible to execute println('a') while this thread is blocked by Thread.sleep()?

import kotlinx.coroutines.*

fun main() = runBlocking(Dispatchers.Default) {
    GlobalScope.launch(Dispatchers.Default) {
        delay(1000L)
        println("a")
    }
    Thread.sleep(3000L)
}

Dispatchers.Default has max limit of threads same as core count of your CPU, for example if you have 4 cores, it could spawn upto 4 threads. — Animesh Sahu
– Animesh Sahu, Commented Jul 22, 2020 at 10:38

Iaroslav Postovalov · Accepted Answer · 2020-07-22 06:06:01Z

3

Default Dispatcher schedules coroutines to its own thread pool, so in your example delay(1000L) and Thread.sleep(3000L) are executed in separate threads.

answered Jul 22, 2020 at 6:06

Iaroslav Postovalov

2,4712 gold badges17 silver badges42 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Why is there code that is executed when the thread is blocked using coroutines?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related