Deadlock when sending message inside ApplicationMessageReceivedHandler

[paolofulgoni]

Describe the bug

If I try to publish a message with AtLeastOnce QoS from the ApplicationMessageReceivedHandler, the message is correctly sent, but the execution of the handler is stuck. It looks like a deadlock.

Everything is working fine with AtMostOnce QoS

Which project is your bug related to?

Client

To Reproduce

I changed a test so that it fails, showing the issue: paolofulgoni@d351a72

Expected behavior

I expect the handler to continue the execution.

[paolofulgoni]

I guess that the Task.Run that I removed from the test was there because of this issue, right?

[SeppPenner]

Which issue? This one #158?

[paolofulgoni]

No, I wasn't referring to that issue. I meant that when @chkr1011 wrote that test, he probably added the Task.Run as a workaround because otherwise the test would fail.

https://github.com/chkr1011/MQTTnet/blob/7aa4d5159c6c8a03b0cce3320beb3c83c5e5fc31/Tests/MQTTnet.Core.Tests/MqttClient_Tests.cs#L40

[SeppPenner]

Ah, okay. Yeah, it might be like that.

[paolofulgoni]

it may be a duplicate of #648

[SeppPenner]

This seems to be very similar, yes.

[paolofulgoni]

OK, so I'm closing the issue. Thanks

[SeppPenner]

Just for reference again: Check out @chkr1011's comments under #648 (comment) and #648 (comment) to find workarounds.