Hi! Sorry if this is a silly question, but I sort of need to be sure about this. I’m looking to implement Channels for some script we’re using, but the Experimental annotation sort of makes me a bit anxious. How experimental are

CoroutineScope.produce()

,

ReceiveChannel<E>.consumeEach{}

and

ProducerScope.send()

? Is there any way to know? I’ve got a working implementation now, but knowing that it may break without warning is a bit scary. Also, is this the wrong place to ask this question? Is the discussion boards a better place?

Since channels are currently stable I’d stick with just using them for now, producers are just syntactic sugar that let you define a coroutine and a channel at the same time. You can easily replace all 3 of those calls with: •

CoroutineScope.produce()

-> define a channel and do a

launch { }

to write values to the channel •

ReceiveChannel<E>.consumeEach{}

->

for (value in channel)

•

ProducerScope.send()

->

channel.send()

in the

launch { }

block mentioned above

Allright, thanks. I was using

consumeEach

because it is important that each element is processed only once - the for loop may see some elements be processed by different workers, no?

When consuming a channel there is a guarantee that each element be processed only once, even when using multiple workers.

consumeEach

is just an alias of the

for

loop.

Wait, what? Isn’t a for loop just a construct that simply iterates elements from start to finish? Which part of it ensures each element is only processed once in case you

repeat(n)

-workers to iterate it? Not that I doubt you at all, it’s just I don’t see how this is safe when processing only once is important. Enlighten me please 🙂

I wrote that runnable example : https://pl.kotl.in/7ZarP7sNa It has 1 producer and 5 consumers ; notice how the numbers from 0 to 10 are only printed once each, and processed by different workers.

I can’t get that to run in that webpage, but I’ll try testing it locally. 🙂 Thanks!

If you have multiple workers listening to the same channel the contents of the channel should be distributed to each worker in a round-robin fashion, they wouldn’t all receive the same elements. This allows fan-out patterns. If you want to broadcast the same elements of the channel to multiple listeners you might try

BroadcastChannel