[Bug] *All* pane misses messages but they reappear after switching to *Recieved* pane and back

[wilx]

What did I do

I have a subscription to a single topic and I am sending messages to another topic in quick succession from the MQTTX GUI client, multiple messages per second by clicking the arrow button at bottom right.

What happened

Sometimes, the All pane does not show all the received messages on the subscribed topic. But when I click to Received pane, it shows all the received messages. Subsequent switch back to All pane then also shows all of the messages.

Expected

MQTTX GUI All pane should always show received messages.

Environment

• OS: Windows 10
• MQTTX version: v1.9.9

More detail

More detail include log information or screenshot

[ysfscream]

Hi, thanks for your feedback.

I am currently unable to replicate the issue you're experiencing. Try clearing the history to see if that makes a difference. The problem could be because many messages are received per second, leading to rendering issues.

Could you please inform me about the approximate number of messages you're receiving and provide some basic information about your system? This information might help us pinpoint and resolve the issue more effectively.

[toshede]

I experience this exact same issue when sending multiple messages on MacOS with the latest three version of MQTTX and can reproduce every now and then.

I mostly experience it when I am sending a message while receiving one at the same time. Or if I am about to receive 4 messages in a very short amount of time, I only get 3 displayed. But when I reopen the app I see all 4 of them.

(It took me a day of debugging and wiresharking to understand that the problem is not in my code.)

Imho this should be very high prioritized, since it is affecting the core functionality of the app.

[ysfscream]

Hi @toshede, you're absolutely right - this is a critical issue affecting MQTTX's core functionality and deserves high priority.

I've been trying to reproduce this consistently but haven't succeeded. Could you help provide more specific details about how you reproduce it? For example:

• Message pub/sub rate (messages per second)
• Message payload size
• Number of messages when the issue occurs
• Are you using any specific payload format?
• Any particular timing between sending and receiving that triggers this more reliably?

Once we can consistently reproduce this, we'll be able to debug and fix the underlying UI rendering issue properly. Your detailed reproduction steps would be extremely helpful.

Thanks for your patience and help in improving MQTTX!

[toshede]

@ysfscream I found a way to reproduce without any additional coding. First to your questions:

• 100-150ms between messages
• 4 bytes each
• 5+ messages
• no
• subscribe to the same topic as sending to for easy debugging

Steps to reproduce:

1. Establish connection to any MQTT broker
2. Subscribe to any topic (for example "test") with QoS1
3. Prepare to send messages to the same topic (from the example above "test") with QoS 1
4. Send some messages
5. Try to send 5+ messages as fast as you can by clicking the send button (gamer skills help)
6. Repeat step 5.
7. Now try to send 5-10 messages as fast as you can again

Result:

-> Messages are missing, but when switching between Received and All they magically appear (see screenshots). The messages must have been received successfully:

I can always reproduce it. I think something with the message order is going wrong, because the messages get rearranged once I switch back to All. The order of the messages in the "All" view does NOT reflect the time order. I have the feeling that multiple bugs are describing the same issue from different angles. I hope this helps.

Edit: One can use Ctrl+Enter / Cmd+Enter to post messages instead of mouse clicks.

[ysfscream]

Thank you all, it should have been fixed in v1.11.1 (release), if there are new problems I will reopen this issue.