Given a block - ```var x: Int = 0 suspend fun mo...

# coroutines

[doodla]

Given a block -

var x: Int = 0

suspend fun modifyX() {
    if (x > 10) {
        x -= 1
    } else {
        x += 1
    }
}

fun main() {
    runBlocking {
        withContext(<http://Dispatchers.IO|Dispatchers.IO>){
            repeat(10) {
                modifyX()
            }
        }
    }
}

Does x need to be @Volatile?

[Zach Klippenstein (he/him) [MOD]]

This code is fully synchronous, let alone multi-threaded, so no. There’s also no reason to use coroutines for this.

[doodla]

Bad example then. I have a suspend function modifying an integer variable. Should this variable be synchronized?

[doodla]

It’s being read in another suspend function.

[Zach Klippenstein (he/him) [MOD]]

Suspendability doesn’t matter for volatility, threading does. Suspension, and coroutines in general, doesn’t necessarily imply multiple threads. Although i think that because the coroutine threading machinery uses atomics, the JVM might guarantee that memory is synchronized correctly between multiple threads here even without volatile.

[doodla]

@Zach Klippenstein (he/him) [MOD] Thanks for your time 🙏. I modified my example to better represent my question.

[Zach Klippenstein (he/him) [MOD]]

Still doesn’t involve any concurrent access to that variable or parallel execution.

[doodla]

Thank you!