A question I have several coroutines ~100 sending a message

Question

A question I have several coroutines ~100 sending a message to a channel This channel reads the messages in a `for message in myChannel ` loop I can see via logging that the events are being send and I see that they are read in the for loop However all except for one of the sending coroutines do not continue and keep being stuck in the suspended state Any idea what could cause this Adding a buffer to the channel seems to help but I would like to know what causes my issue

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

How are you creating your channel

David Stibbe · Answer

`Channel `

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

The say gt The `Channel capacity ` factory function is used to create channels of different kinds depending on the value of the `capacity` integer gt When `capacity` is 0 it creates a rendezvous channel This channel does not have any buffer at all An element is transferred from the sender to the receiver only when and invocations meet in time rendezvous so suspends until another coroutine invokes and suspends until another coroutine invokes bold added In `RENDEZVOUS` mode Send suspends until another coroutine invokes receive And if you look at the for the `Channel ` function you ll see the default capacity is `RENDEZVOUS`

David Stibbe · Answer

yes

David Stibbe · Answer

and that is how I expect it to work

David Stibbe · Answer

the messages are received but the sending coroutines remains suspended

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

What dispatcher are you using

David Stibbe · Answer

DefaultDispatcher

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

Are all the threads blocked somehow If not I m not sure what s going on

David Stibbe · Answer

No idea what could block them

Joffrey · Answer

Can you share some code that reproduces the issue As < Zach Klippenstein he him MOD > suggested it might be due to thread starvation For instance if what you do in the loop blocks the thread

David Stibbe · Answer

I will provide a snippet later today

streetsofboston · Answer

Are you sending messages back to the original source actor ie process that puts messages into the source Channel A circular graph of actors can cause locks

David Stibbe · Answer

Unfortunately no S

David Stibbe · Answer

< Joffrey> < Zach Klippenstein he him MOD > < Stylianos Gakis> < streetsofboston> Sorry for not posting sooner I have found the cause and the solution of my problem The cause was Ktor The client starts blocking after a certain number of calls I was running a test in which I did 100 simultaneous calls using Ktor s 2 0 `testApplication` function

David Stibbe · Answer

The solution was to configure the client to use the CIO engine

David Stibbe · Answer

```val client = createClient engine CIO install WebSockets ```

David Stibbe · Answer

also using websockets