BluezDBus: freezing on connect+scan in parallel task

[devbis]

• bleak version: 0.13.0
• Python version: 3.9
• Operating System: Linux, OpenWrt
• BlueZ version (bluetoothctl -v) in case of Linux: 5.56

Description

I'm running two separate tasks: one is starting scanning and the second one is trying to connect to a device. The problem is that despite of timeout device is not connecting and the code doesn't return from connect() coroutine.

What I Did

The first iteration: I ran the client.connect() with wait_for timeout and it fails in the first run and succeeds in other tries.

The second iteration: I put debug prints in the bleak backend code and found the code that "hangs". The problem is inside this code: https://github.com/hbldh/bleak/blob/v0.13.0/bleak/backends/bluezdbus/scanner.py#L148-L155

Here is the output (from both tasks):

-- call bus GetManagedObjects
-- call bus GetManagedObjects
-- call bus SetDiscoveryFilter
-- call bus SetDiscoveryFilter
-- call bus StartDiscovery
-- call bus StartDiscovery
-- StartDiscovery done

(only a single print after StartDiscovery)

Replacing the mentioned code to the following worked as well

        reply = await asyncio.wait_for(
          self._bus.call(
            Message(
                destination=defs.BLUEZ_SERVICE,
                path=self._adapter_path,
                interface=defs.ADAPTER_INTERFACE,
                member="StartDiscovery",
            )
          ), 
          timeout=3,
        )

I suppose somehow bluez responses to the first StartDiscovery only. I guess a timeout can solve freezing if there is no more elegant solution.

[dlech]

Same as #361?

[devbis]

It may relate. I need to check simultaneous connections to a couple of devices.

[dlech]

Closing since the BlueZ backend has changed significantly since this was reported.