[Python] Application error with multiple devices and subscriptions

[bradmartin333]

Stuck battling a multi-device application crash. Found a fix, but it requires running 2 instances of the same application. Not sure where the issue lies. Let me know if I am being too vague / more info needed.

Pseudocode

main starts new thread with a target that performs something like:

adapter = get_one_valid_adapter()
adapter.scan_for(5000)
peripherals = adapter.scan_get_results()
# device_a
device_a, service_uuid_a, characteristic_uuid_a = find_connect_device_a(peripherals)
device_a.notify(service_uuid_a, characteristic_uuid_a, lambda data: print(f"Notification: {data}"))
# Repeat for a hypothetical device_b

I have also tried:

# device_a
adapter = get_one_valid_adapter()
adapter.scan_for(5000)
peripherals = adapter.scan_get_results()
device_a, service_uuid_a, characteristic_uuid_a = find_device_a(peripherals)
device_a.notify(service_uuid_a, characteristic_uuid_a, lambda data: 
print(f"Notification: {data}"))
# Repeat for a hypothetical device_b

Issue

• device_a's characteristic notifies at 250Hz and device_b notifies at 1Hz. The data sometimes seems to get jumbled and the python program abruptly exists with no exceptions whatsoever across all main and dummy threads.
  • By jumbled, I mean I will start getting crc16 check errors where I haven't seen any before with a single device
• The only indication that there was an error is in the Windows event logs. I have not tried on Linux, yet.

Working solution

• Now, I run 2 separate python programs with identical code but for only one device and that works
• I have a single Bluetooth 5.0 adapter on Windows

Questions

• Is this the intended behavior?
• Could it be an issue with spawning a thread to discover and connect?

[Jah-On]

I'm also experiencing a similar issue on Windows where the whole app silently exits upon trying to process a notification.

[Jah-On]

I'll try writing a C++ version to see if it's the Python FFI or something in the C++ back end.

[Jah-On]

This appears to be an issue related to FFI as notifications in C++ work fine.