Publisher confirm tests fail sporadically

[michaelklishin]

Publisher confirms test sporadically fails for no known reason. This seemingly only happens when a lot of tests are executed at the same time.

Anecdotal evidence leads me to believe it could a dispatch queue interference. That's just a totally unconfirmed hypothesis at the moment. Possibly related to #56.

I am yet to capture traffic when this happens. Now that we have user-provided connection name support (#156), it should be easier to identify this test's connection in both Wireshark and server logs.

[SimonErm]

I found some more weird behaviour with afterConfirm. This time i send 6 messages (all delivered succesful), but receive 1 ack(first call of afterConfirm handler), 1 with neither ack nor nack(next call) and then 4 nacks. Furthermore channel.basicPublish always returned 1. Shouldn't it at least increment?
This problem doesn't make any sense to me.

[michaelklishin]

Channel#basicPublish shouldn't have any return value. There is no response for basic.publish and related payload frames in the protocol.

[SimonErm]

I found it here:

rabbitmq-objc-client/RMQClient/RMQChannel.h

Line 240 in 9bee6f0

* @return A sequence number that correlates to the numbers sent to the afterConfirmation block (when publisher confirmations are enabled).

[michaelklishin]

It was a mistake. No other client returns anything like this from basicPublish. Let's. focus on the issue at hand.

[SimonErm]

I did an example repo: https://github.com/SimonErm/rabbitmq-objc-client-after-confirm-reproduction .
Just checkout and run npm install and docker run -p 5672:5672 -e RABBITMQ_DEFAULT_VHOST=test rabbitmq:3
Then you can set a breakpoint in the ConfirmationCallback in AfterConfirmReproduce.swift and run the App from objcRabbitmqAfterConfirm workspace

[SimonErm]

I got it working for me by using DipatchSemaphore and registering afterConfirm after publish like it's done in

rabbitmq-objc-client/RMQClientIntegrationTests/ChannelIntegrationTest.swift

Line 70 in 5a84580

let semaphore = DispatchSemaphore(value: 0)

[michaelklishin]

@SimonErm thanks for following-up. I should be able to pick up your repro example in the 2nd half of next week. So it's not been forgotten.

[michaelklishin]

Curiously I no longer can reproduce.

[michaelklishin]

This example does not await confirmations, so the method is as safe as if confirms were not used at all.

I had a different problem but with XCode 11 it seems to be gone. Oh well :)