Reduce access log overhead when logging is disabled

CHANGES/7240.feature

@@ -0,0 +1 @@
+Turned access log into no-op when the logger is disabled.

aiohttp/web_log.py

@@ -189,6 +189,9 @@ def _format_line(
         return [(key, method(request, response, time)) for key, method in self._methods]
 
     def log(self, request: BaseRequest, response: StreamResponse, time: float) -> None:
+        if not self.logger.isEnabledFor(logging.INFO):
+            # Avoid formatting the log line if it will not be emitted.
+            return
         try:
             fmt_info = self._format_line(request, response, time)
 

tests/test_web_log.py

@@ -1,5 +1,6 @@
 # type: ignore
 import datetime
+import logging
 import platform
 import sys
 from typing import Any
@@ -251,3 +252,20 @@ def log(self, request, response, time):
     resp = await client.get("/")
     assert 200 == resp.status
     assert msg == "contextvars: uuid"
+
+
+def test_logger_does_nothing_when_disabled(caplog: pytest.LogCaptureFixture) -> None:
+    """Test that the logger does nothing when the log level is disabled."""
+    mock_logger = logging.getLogger("test.aiohttp.log")
+    mock_logger.setLevel(logging.INFO)
+    access_logger = AccessLogger(mock_logger, "%b")
+    access_logger.log(
+        mock.Mock(name="mock_request"), mock.Mock(name="mock_response"), 42
+    )
+    assert "mock_response" in caplog.text
+    caplog.clear()
+    mock_logger.setLevel(logging.WARNING)
+    access_logger.log(
+        mock.Mock(name="mock_request"), mock.Mock(name="mock_response"), 42
+    )
+    assert "mock_response" not in caplog.text