When the program exits, Bleak BLE connection is not released.

[zapta]

• bleak version: 0.19.5
• Python version: 3.10.6
• Operating System: Ubuntu 22.04.1 LTS
• BlueZ version (bluetoothctl -v) in case of Linux: bluetoothctl: 5.64

Description

If a bleak program exits, the BLE connection is still maintained forever. I encountered it only on linux. On Windows the connection is terminated about 30 secs later and IIRC, on macosc, it terminated immediately. Same if I connect from the nRF Connect app on my phone.

To reproduce

1. Have a connectable BLE device and identify it's address. (E.g. the ESP32 device marked '2' I email a week or two ago).
2. Create a python file with the test program below and edit the device address.
3. Run the program once, it will connect to the device and exit.
4. Check if the connection is still maintained. For example, look at the device connection indicator if available (fast blinking LED in ESP32 '2'), and test if the device returned to advertising mode or not. With Linux, the device stay connected for ever.
5. Turn off Bluetooth on Linux and observe how the connection on the device is disconnected.

What I Did

Test program:

import asyncio
import platform
import sys
from bleak import BleakClient, BleakScanner

# Adapt to your actual device.
device_address = "0C:8B:95:F2:B4:36"

print(f"OS: {platform.platform()}", flush=True)
print(f"Platform:: {platform.uname()}", flush=True)
print(f"Python {sys.version}", flush=True)

async def test():
    global client
    print(f"Trying to connect to {device_address}", flush=True)
    device = await BleakScanner.find_device_by_address(device_address, timeout=10.0)
    assert device
    client = BleakClient(device)
    assert client
    await client.connect(timeout=10.0)
    assert client.is_connected
    print(f"Connected", flush=True)
    print(f"Test done", flush=True)

event_loop = asyncio.new_event_loop()
event_loop.run_until_complete(test())

Logs

user@linux:/projects/ble_stepper_motor_analyzer/repo/app/test$ python3 connection_cleanup.py
OS: Linux-5.19.0-32-generic-x86_64-with-glibc2.35
Platform:: uname_result(system='Linux', node='linux', release='5.19.0-32-generic', version='#3322.04.1-Ubuntu SMP PREEMPT_DYNAMIC Mon Jan 30 17:03:34 UTC 2', machine='x86_64')
Python 3.10.6 (main, Nov 14 2022, 16:10:14) [GCC 11.3.0]
Trying to connect to 0C:8B:95:F2:B4:36
2023-02-16 09:13:04,096 bleak.backends.bluezdbus.manager DEBUG: initial properties: {'/org/bluez': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.AgentManager1': {}, 'org.bluez.ProfileManager1': {}}, '/org/bluez/hci0': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Adapter1': {'Address': 'EC:63:D7:F1:C7:8B', 'AddressType': 'public', 'Name': 'linux', 'Alias': 'linux', 'Class': 0, 'Powered': True, 'Discoverable': False, 'DiscoverableTimeout': 180, 'Pairable': False, 'PairableTimeout': 0, 'Discovering': False, 'UUIDs': ['00001133-0000-1000-8000-00805f9b34fb', '0000110e-0000-1000-8000-00805f9b34fb', '00001105-0000-1000-8000-00805f9b34fb', '00001132-0000-1000-8000-00805f9b34fb', '00001200-0000-1000-8000-00805f9b34fb', '00001104-0000-1000-8000-00805f9b34fb', '00005005-0000-1000-8000-0002ee000001', '00001108-0000-1000-8000-00805f9b34fb', '0000110c-0000-1000-8000-00805f9b34fb', '00001801-0000-1000-8000-00805f9b34fb', '0000112f-0000-1000-8000-00805f9b34fb', '0000110b-0000-1000-8000-00805f9b34fb', '0000180a-0000-1000-8000-00805f9b34fb', '00001800-0000-1000-8000-00805f9b34fb', '0000111f-0000-1000-8000-00805f9b34fb', '0000110a-0000-1000-8000-00805f9b34fb', '00001106-0000-1000-8000-00805f9b34fb'], 'Modalias': 'usb:v1D6Bp0246d0540', 'Roles': ['central', 'peripheral']}, 'org.freedesktop.DBus.Properties': {}, 'org.bluez.GattManager1': {}, 'org.bluez.Media1': {}, 'org.bluez.NetworkServer1': {}, 'org.bluez.LEAdvertisingManager1': {'ActiveInstances': 0, 'SupportedInstances': 5, 'SupportedIncludes': ['tx-power', 'appearance', 'local-name']}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': '0C:8B:95:F2:B4:36', 'AddressType': 'public', 'Name': 'STP-0C8B95F2B436', 'Alias': 'STP-0C8B95F2B436', 'Paired': False, 'Trusted': False, 'Blocked': False, 'LegacyPairing': False, 'Connected': False, 'UUIDs': ['00001800-0000-1000-8000-00805f9b34fb', '00001801-0000-1000-8000-00805f9b34fb', '6b6a78d7-8ee0-4a26-ba7b-62e357dd9720'], 'Adapter': '/org/bluez/hci0', 'ServicesResolved': False}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattService1': {'UUID': '6b6a78d7-8ee0-4a26-ba7b-62e357dd9720', 'Device': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36', 'Primary': True, 'Includes': []}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char003c': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '0000ff07-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['read']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char003a': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '0000ff06-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['write']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char0038': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '0000ff05-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['read']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char0036': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '0000ff04-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['read']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char0034': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '0000ff03-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['read']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char0031': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '0000ff02-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Notifying': False, 'Flags': ['read', 'notify'], 'NotifyAcquired': False}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char0031/desc0033': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'UUID': '00002902-0000-1000-8000-00805f9b34fb', 'Characteristic': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char0031', 'Value': bytearray(b'')}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char002f': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '0000ff01-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['read']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char002d': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '00002a29-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['read']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char002b': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '00002a26-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['read']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028/char0029': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '00002a24-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0028', 'Value': bytearray(b''), 'Flags': ['read']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0001': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattService1': {'UUID': '00001801-0000-1000-8000-00805f9b34fb', 'Device': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36', 'Primary': True, 'Includes': []}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0001/char0002': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattCharacteristic1': {'UUID': '00002a05-0000-1000-8000-00805f9b34fb', 'Service': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0001', 'Value': bytearray(b''), 'Notifying': False, 'Flags': ['indicate']}, 'org.freedesktop.DBus.Properties': {}}, '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0001/char0002/desc0004': {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.GattDescriptor1': {'UUID': '00002902-0000-1000-8000-00805f9b34fb', 'Characteristic': '/org/bluez/hci0/dev_0C_8B_95_F2_B4_36/service0001/char0002', 'Value': bytearray(b'')}, 'org.freedesktop.DBus.Properties': {}}}
2023-02-16 09:13:04,217 bleak.backends.bluezdbus.manager DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0): ['org.bluez.Adapter1', {'Discovering': <dbus_fast.signature.Variant ('b', True)>}, []]
2023-02-16 09:13:04,269 bleak.backends.bluezdbus.manager DEBUG: received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_30_E2_83_7C_F3_11', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': <dbus_fast.signature.Variant ('s', 30:E2:83:7C:F3:11)>, 'AddressType': <dbus_fast.signature.Variant ('s', public)>, 'Name': <dbus_fast.signature.Variant ('s', BLE Device-7CF311)>, 'Alias': <dbus_fast.signature.Variant ('s', BLE Device-7CF311)>, 'Paired': <dbus_fast.signature.Variant ('b', False)>, 'Trusted': <dbus_fast.signature.Variant ('b', False)>, 'Blocked': <dbus_fast.signature.Variant ('b', False)>, 'LegacyPairing': <dbus_fast.signature.Variant ('b', False)>, 'RSSI': <dbus_fast.signature.Variant ('n', -71)>, 'Connected': <dbus_fast.signature.Variant ('b', False)>, 'UUIDs': <dbus_fast.signature.Variant ('as', ['0000ff12-0000-1000-8000-00805f9b34fb'])>, 'Adapter': <dbus_fast.signature.Variant ('o', /org/bluez/hci0)>, 'ServicesResolved': <dbus_fast.signature.Variant ('b', False)>}, 'org.freedesktop.DBus.Properties': {}}]
2023-02-16 09:13:04,386 bleak.backends.bluezdbus.manager DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_0C_8B_95_F2_B4_36): ['org.bluez.Device1', {'RSSI': <dbus_fast.signature.Variant ('n', -50)>, 'TxPower': <dbus_fast.signature.Variant ('n', 3)>}, []]
2023-02-16 09:13:04,394 bleak.backends.bluezdbus.manager DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_0C_8B_95_F2_B4_36): ['org.bluez.Device1', {}, ['TxPower', 'RSSI']]
2023-02-16 09:13:04,395 bleak.backends.bluezdbus.manager DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_30_E2_83_7C_F3_11): ['org.bluez.Device1', {}, ['RSSI']]
2023-02-16 09:13:04,397 bleak.backends.bluezdbus.manager DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0): ['org.bluez.Adapter1', {'Discovering': <dbus_fast.signature.Variant ('b', False)>}, []]
2023-02-16 09:13:04,402 bleak.backends.bluezdbus.client DEBUG: Connecting to device @ 0C:8B:95:F2:B4:36
2023-02-16 09:13:04,414 bleak.backends.bluezdbus.client DEBUG: Connecting to BlueZ path /org/bluez/hci0/dev_0C_8B_95_F2_B4_36
2023-02-16 09:13:04,517 bleak.backends.bluezdbus.manager DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_0C_8B_95_F2_B4_36): ['org.bluez.Device1', {'Connected': <dbus_fast.signature.Variant ('b', True)>}, []]
2023-02-16 09:13:05,171 bleak.backends.bluezdbus.manager DEBUG: received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_0C_8B_95_F2_B4_36): ['org.bluez.Device1', {'ServicesResolved': <dbus_fast.signature.Variant ('b', True)>}, []]
Connected
Test done
user@linux:~/projects/ble_stepper_motor_analyzer/repo/app/test$

[dlech]

If you want this behavior, you need to use asyncio.run(test()) and async with BleakClient(device) as client:.

[zapta]

Thanks @dlech, I presume you mean the code below which indeed work. In my actual program I have seperate function to establish the connection, interacting with the device and closing the connection, so I would like to have a global client variable that the various pieces can use.

How do I break the code in 'async with BleakClient(device) as client:' to three three separate parts with a global variable for the client? (similar to the 'client' variable in my original code above).

(My app uses pyqtgraph which is a framework with inversion of control so I am not in control of the mail code, just getting callbacks on certain events).

import asyncio
import platform
import sys
import time
import signal
from bleak import BleakClient, BleakScanner
import signal

# Adapt to your actual device.
device_address = "0C:8B:95:F2:B4:36"

signal.signal(signal.SIGINT, lambda number, frame: sys.exit())

print(f"OS: {platform.platform()}", flush=True)
print(f"Platform:: {platform.uname()}", flush=True)
print(f"Python {sys.version}", flush=True)

async def test():
    #global client
    print(f"Trying to connect to {device_address}", flush=True)
    device = await BleakScanner.find_device_by_address(device_address, timeout=10.0)
    assert device
    async with BleakClient(device) as client:
        assert client.is_connected
        print(f"Connected", flush=True)
        print(f"Waiting 5 secs...", flush=True)
        time.sleep(5.0)
        print(f"Closing...", flush=True)
        assert client.is_connected
        await client.disconnect()
        print(f"Test done", flush=True)

asyncio.run(test())

[dlech]

You can create tasks and use asyncio.gather() to run 3 tasks in parallel