Split mqtt subscribe and unsubscribe calls to smaller chunks (#118035)

homeassistant/components/mqtt/client.py

@@ -34,6 +34,7 @@ from homeassistant.helpers.start import async_at_started
 from homeassistant.helpers.typing import ConfigType
 from homeassistant.loader import bind_hass
 from homeassistant.util.async_ import create_eager_task
+from homeassistant.util.collection import chunked_or_all
 from homeassistant.util.logging import catch_log_exception
 
 from .const import (
@@ -100,6 +101,9 @@ UNSUBSCRIBE_COOLDOWN = 0.1
 TIMEOUT_ACK = 10
 RECONNECT_INTERVAL_SECONDS = 10
 
+MAX_SUBSCRIBES_PER_CALL = 500
+MAX_UNSUBSCRIBES_PER_CALL = 500
+
 type SocketType = socket.socket | ssl.SSLSocket | mqtt.WebsocketWrapper | Any
 
 type SubscribePayloadType = str | bytes  # Only bytes if encoding is None
@@ -905,11 +909,15 @@ class MQTT:
         self._pending_subscriptions = {}
 
         subscription_list = list(subscriptions.items())
-        result, mid = self._mqttc.subscribe(subscription_list)
+
+        for chunk in chunked_or_all(subscription_list, MAX_SUBSCRIBES_PER_CALL):
+            result, mid = self._mqttc.subscribe(chunk)
 
             if _LOGGER.isEnabledFor(logging.DEBUG):
                 for topic, qos in subscriptions.items():
-                _LOGGER.debug("Subscribing to %s, mid: %s, qos: %s", topic, mid, qos)
+                    _LOGGER.debug(
+                        "Subscribing to %s, mid: %s, qos: %s", topic, mid, qos
+                    )
             self._last_subscribe = time.monotonic()
 
             if result == 0:
@@ -925,10 +933,11 @@ class MQTT:
         topics = list(self._pending_unsubscribes)
         self._pending_unsubscribes = set()
 
-        result, mid = self._mqttc.unsubscribe(topics)
+        for chunk in chunked_or_all(topics, MAX_UNSUBSCRIBES_PER_CALL):
+            result, mid = self._mqttc.unsubscribe(chunk)
             _raise_on_error(result)
             if _LOGGER.isEnabledFor(logging.DEBUG):
-            for topic in topics:
+                for topic in chunk:
                     _LOGGER.debug("Unsubscribing from %s, mid: %s", topic, mid)
 
             await self._async_wait_for_mid(mid)

tests/components/mqtt/test_init.py

@@ -44,7 +44,7 @@ from homeassistant.const import (
     UnitOfTemperature,
 )
 import homeassistant.core as ha
-from homeassistant.core import CoreState, HomeAssistant, callback
+from homeassistant.core import CALLBACK_TYPE, CoreState, HomeAssistant, callback
 from homeassistant.exceptions import HomeAssistantError, ServiceValidationError
 from homeassistant.helpers import device_registry as dr, entity_registry as er, template
 from homeassistant.helpers.entity import Entity
@@ -2816,6 +2816,59 @@ async def test_mqtt_subscribes_in_single_call(
     ]
 
 
+@pytest.mark.parametrize(
+    "mqtt_config_entry_data",
+    [
+        {
+            mqtt.CONF_BROKER: "mock-broker",
+            mqtt.CONF_BIRTH_MESSAGE: {},
+            mqtt.CONF_DISCOVERY: False,
+        }
+    ],
+)
+@patch("homeassistant.components.mqtt.client.MAX_SUBSCRIBES_PER_CALL", 2)
+@patch("homeassistant.components.mqtt.client.MAX_UNSUBSCRIBES_PER_CALL", 2)
+@patch("homeassistant.components.mqtt.client.SUBSCRIBE_COOLDOWN", 0.0)
+@patch("homeassistant.components.mqtt.client.INITIAL_SUBSCRIBE_COOLDOWN", 0.0)
+async def test_mqtt_subscribes_and_unsubscribes_in_chunks(
+    hass: HomeAssistant,
+    mqtt_client_mock: MqttMockPahoClient,
+    mqtt_mock_entry: MqttMockHAClientGenerator,
+    record_calls: MessageCallbackType,
+) -> None:
+    """Test chunked client subscriptions."""
+    mqtt_mock = await mqtt_mock_entry()
+    # Fake that the client is connected
+    mqtt_mock().connected = True
+
+    mqtt_client_mock.subscribe.reset_mock()
+    unsub_tasks: list[CALLBACK_TYPE] = []
+    unsub_tasks.append(await mqtt.async_subscribe(hass, "topic/test1", record_calls))
+    unsub_tasks.append(await mqtt.async_subscribe(hass, "home/sensor1", record_calls))
+    unsub_tasks.append(await mqtt.async_subscribe(hass, "topic/test2", record_calls))
+    unsub_tasks.append(await mqtt.async_subscribe(hass, "home/sensor2", record_calls))
+    await hass.async_block_till_done()
+    # Make sure the debouncer finishes
+    await asyncio.sleep(0.2)
+
+    assert mqtt_client_mock.subscribe.call_count == 2
+    # Assert we have a 2 subscription calls with both 2 subscriptions
+    assert len(mqtt_client_mock.subscribe.mock_calls[0][1][0]) == 2
+    assert len(mqtt_client_mock.subscribe.mock_calls[1][1][0]) == 2
+
+    # Unsubscribe all topics
+    for task in unsub_tasks:
+        task()
+    await hass.async_block_till_done()
+    # Make sure the debouncer finishes
+    await asyncio.sleep(0.2)
+
+    assert mqtt_client_mock.unsubscribe.call_count == 2
+    # Assert we have a 2 unsubscribe calls with both 2 topic
+    assert len(mqtt_client_mock.unsubscribe.mock_calls[0][1][0]) == 2
+    assert len(mqtt_client_mock.unsubscribe.mock_calls[1][1][0]) == 2
+
+
 async def test_default_entry_setting_are_applied(
     hass: HomeAssistant,
     device_registry: dr.DeviceRegistry,