Improve logging and handling when websocket gets behind (#86854)

fixes undefined

tests/components/websocket_api/test_http.py

@@ -67,6 +67,50 @@ async def test_pending_msg_peak(hass, mock_low_peak, hass_ws_client, caplog):
     assert "Client unable to keep up with pending messages" in caplog.text
 
 
+async def test_pending_msg_peak_but_does_not_overflow(
+    hass, mock_low_peak, hass_ws_client, caplog
+):
+    """Test pending msg hits the low peak but recovers and does not overflow."""
+    orig_handler = http.WebSocketHandler
+    instance: http.WebSocketHandler | None = None
+
+    def instantiate_handler(*args):
+        nonlocal instance
+        instance = orig_handler(*args)
+        return instance
+
+    with patch(
+        "homeassistant.components.websocket_api.http.WebSocketHandler",
+        instantiate_handler,
+    ):
+        websocket_client = await hass_ws_client()
+
+    assert instance is not None
+
+    # Kill writer task and fill queue past peak
+    for _ in range(5):
+        instance._to_write.put_nowait(None)
+
+    # Trigger the peak check
+    instance._send_message({})
+
+    # Clear the queue
+    while instance._to_write.qsize() > 0:
+        instance._to_write.get_nowait()
+
+    # Trigger the peak clear
+    instance._send_message({})
+
+    async_fire_time_changed(
+        hass, utcnow() + timedelta(seconds=const.PENDING_MSG_PEAK_TIME + 1)
+    )
+
+    msg = await websocket_client.receive()
+    assert msg.type == WSMsgType.TEXT
+
+    assert "Client unable to keep up with pending messages" not in caplog.text
+
+
 async def test_non_json_message(hass, websocket_client, caplog):
     """Test trying to serialize non JSON objects."""
     bad_data = object()