Hi can someone explain me why consuming the channel suspends forever?

private val packetChannel: Channel<ResponsePacket> = Channel(Channel.UNLIMITED)

    suspend fun sendPacketWithBatchResponse(packet: RequestPacket): List<ResponsePacket> {
        sendPacketWithAcknowledgement(packet)
        val packets = mutableListOf<ResponsePacket>()

        for (item in packetChannel) {
            Timber.e("here")
            packets.add(item)
        }

        // Unreached code
        return packets
    }

    // Another non-suspending function which is decoupled from the consuming function
    fun produce() {
        ...
        packetChannel.offer(packet)
    }

The goal is to offer multiple packets (~20) to the channel and when finished jump to the

sendPacketWithBatchResponse

and consume these packets all at once but

sendPacketWithBatchResponse

never returns and I don't know why

Not sure with a quick glance, but maybe good to confirm that your

offer

call in

produce

returned

true

?

@travis The channel have to be kept open.

take

is deprecated but what works is:

val packets = mutableListOf<ResponsePacket>() 
       repeat(20) {
            packets.add(packetChannel.receive())
        }

But why does this work and something like

packetChannel.toList()

not?

receive

will receive a single time. It suspends until an item is available and takes it from the

Channel

. So with the

repeat

you're essentially saying you want to pull

20

items from the

Channel

(one after another), then you're done.

toList

will wait until the

Channel

closes before it is considered "done". In other words, it needs some way to know how many items to put in the

List

it is returning,

Channel

termination is how it decides it is time to return the list of items.

Thanks for your input, got it now