[Bug/Feature] Add proper safeguards to prevent full system crashes

[Aestyo]

What did I do

I connected to a broker using MQTTX and subscribed to a topic that receives a high volume of messages.

What happened

My entire computer completely froze and became totally unresponsive. The system locked up so hard that I lost all access to keyboard, mouse, UI, everything. The only possible action was to force a full reboot. This is 100% reproducible and only happens when using MQTTX.

Expected

MQTTX should never cause a full system freeze under any circumstances. A software client must have proper safeguards, rate-limiting, buffering, or at the very least crash itself not the entire operating system. It is absolutely unacceptable that a simple electron app can lead to a total system lock-up.

Environment

• OS: Windows 11 (latest patches applied)

• MQTTX version: v1.12.0

• Hardware:

  • Intel Core Ultra 7 165H
  • 32 GB RAM
  • NVIDIA RTX 2000 Ada Generation Laptop GPU

More detail

There is nothing particularly useful in the logs before the freeze, except for the following entries:

[2025-11-13 10:48:25] [ERROR] Error subscribing to topic: Error: client disconnecting
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)
[2025-11-13 10:48:25] [INFO] Message buffer mode enabled (> 30/s)

No desktop application should ever be capable of freezing an entire operating system. The lack of control, safety mechanisms, or even basic stability is disappointing.

[ysfscream]

Hi @Aestyo,

We sincerely apologize for the system freeze you experienced - this should never happen.

To help us reproduce and optimize this issue, could you please share the approximate message rate (messages per second) and payload size?

Thank you!

[Aestyo]

Hi,

The message rate is roughly around 1,000 messages per second, but I suspect the bigger issue might actually be the ~4,000 retained messages on that topic. For EMQX Enterprise and other MQTT clients, these numbers aren't so much. They handle this load without any stability issues. And yet this is only our test environment, not even our production environment.

I also reproduced the issue on another machine with the exact same hardware, and the result is identical: forcing a graphics driver reload (using the Windows shortcut) briefly brings the interface back and allows me to press Ctrl+Alt+Del, but it still becomes impossible to return to the desktop afterward.

Let me know if you need anything else.