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Hi! Does anyone have any pointer in how you could debug a coroutine that doesn’t seem to wake up at the correct time? I have a test where a message is picked up on a queue which results in a request towards a stub (which returns 404). The problem is that even though the stub is up and ready it seems that the coroutine that is suspending (it’s a post from the ktor http client) is not “woken up” until after about 30 seconds when the same message gets republished on the queue. The coroutine that I suspect to not be woken up correctly is surrounded in a repeat, I see that first repeat happen but then it just goes silent

Looks like some problem in coroutine adapter implementation, or may be some deadlock

When coroutine is not unsuspended it's like do not receive call back, so there is no simple way to debug, except check every step of this code invocation

Do you use channels? Or just suspend functions?

Just suspending functions, one of them is a http post with the ktor client (which hits a 404 endpoint), the other "suspension point" is that the post is surrounded by a repeat if it does not succeed and then hits a delay()

Are you sure that it is really never return? Maybe 30 second before repeat is not enough?

ah, so the logic is like this:
Do a http call  (<http://ktorClient.post|ktorClient.post> - suspending function)
If that fails, try again within 0.1 seconds - (delay, suspending function)
If that fails, try again within 0.5 seconds - (delay, suspending function)
If that fails try again within 1 second - (delay, suspending function)
if that fails -&gt; throw Exception


I have dummy debug logs around pretty much everything at this point and even though the ktorClient calls a 404-endpoint (which returns immediately) it doesn’t return and log that it will retry until 30 seconds later. The message that triggers this whole loop has a “visibility timeout” of 30 seconds so the behavior that I am seeing is that when the message get’s republished suddenly the first coroutine wakes up as well and they are both dealt with

It may be some bug of course, but hard to say without reproduction, maybe you could create some sample and report to ktor issue tracker