wave is it ok if I open a subscription to a broadcastChanne kotlinlang #coroutines

👋 is it ok if I open a subscription to a broadcastChannel and consume the items inside a coroutine and when I'm not interested on receiving items from the channel I just cancel the coroutine or do i need to explicitly close the channel?

will that leave the channel open and will leak memory?

gildor

01/30/2019, 4:40 PM

Cancel coroutine is enough

julioyg

01/30/2019, 4:40 PM

but after closing the coroutine if I check

isClosedForReceive

it's

false

...

Copy code

fun main() {
    var channel: ReceiveChannel<String>? = null

    var broadcastChannel = BroadcastChannel<String>(1)

    val job = GlobalScope.launch {
        channel = broadcastChannel.openSubscription()
    }

    job.cancel()

    Thread.sleep(1000)

    println("is closed ${channel!!.isClosedForReceive}")
}

that prints

false

is that ok?

(sorry, just to make sure we are both talking about the same thing)

Allan Wang

01/30/2019, 6:45 PM

I actually have this by design, as I use BroadcastChannel as a replacement for RxJava's subjects. I intentionally keep it open even outside the lifecycle, in cases other components offer values beyond the lifecycle. This avoids the crashes, and so long as you aren't dealing with UI related models, I think it should be fine

Relevant issue I asked: https://github.com/Kotlin/kotlinx.coroutines/issues/937

julioyg

01/30/2019, 7:21 PM

my bad, it gets closed if I call

consumeEach

thanks bot for the help

@Allan Wang you don't need to keep the channel open, because it's a

BroadcastChannel

so when you call

openSubscription

it creates a new channel, so (reading the github issue) even if you close the channel returned by

openSubscription

you can still send items to the

BroadcastChannel

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