Avoid passing client writer to response when already finished (#9485)

CHANGES/9485.misc.rst

@@ -0,0 +1 @@
+Improved performance of sending client requests when the writer can finish synchronously -- by :user:`bdraco`.

aiohttp/client_reqrep.py

@@ -284,17 +284,11 @@ def _writer(self) -> Optional["asyncio.Task[None]"]:
         return self.__writer
 
     @_writer.setter
-    def _writer(self, writer: Optional["asyncio.Task[None]"]) -> None:
+    def _writer(self, writer: "asyncio.Task[None]") -> None:
         if self.__writer is not None:
             self.__writer.remove_done_callback(self.__reset_writer)
         self.__writer = writer
-        if writer is None:
-            return
-        if writer.done():
-            # The writer is already done, so we can reset it immediately.
-            self.__reset_writer()
-        else:
-            writer.add_done_callback(self.__reset_writer)
+        writer.add_done_callback(self.__reset_writer)
 
     def is_ssl(self) -> bool:
         return self.url.scheme in _SSL_SCHEMES
@@ -701,6 +695,7 @@ async def send(self, conn: "Connection") -> "ClientResponse":
         await writer.write_headers(status_line, self.headers)
         coro = self.write_bytes(writer, conn)
 
+        task: Optional["asyncio.Task[None]"]
         if sys.version_info >= (3, 12):
             # Optimization for Python 3.12, try to write
             # bytes immediately to avoid having to schedule
@@ -709,7 +704,11 @@ async def send(self, conn: "Connection") -> "ClientResponse":
         else:
             task = self.loop.create_task(coro)
 
-        self._writer = task
+        if task.done():
+            task = None
+        else:
+            self._writer = task
+
         response_class = self.response_class
         assert response_class is not None
         self.response = response_class(
@@ -785,7 +784,7 @@ def __init__(
         method: str,
         url: URL,
         *,
-        writer: "asyncio.Task[None]",
+        writer: "Optional[asyncio.Task[None]]",
         continue100: Optional["asyncio.Future[bool]"],
         timer: Optional[BaseTimerContext],
         request_info: RequestInfo,
@@ -802,7 +801,8 @@ def __init__(
         self._real_url = url
         self._url = url.with_fragment(None) if url.raw_fragment else url
         self._body: Optional[bytes] = None
-        self._writer = writer
+        if writer is not None:
+            self._writer = writer
         self._continue = continue100  # None by default
         self._closed = True
         self._history: Tuple[ClientResponse, ...] = ()
@@ -846,8 +846,8 @@ def _writer(self, writer: Optional["asyncio.Task[None]"]) -> None:
         if writer is None:
             return
         if writer.done():
-            # The writer is already done, so we can reset it immediately.
-            self.__reset_writer()
+            # The writer is already done, so we can clear it immediately.
+            self.__writer = None
         else:
             writer.add_done_callback(self.__reset_writer)
 

tests/test_client_request.py

@@ -1344,7 +1344,7 @@ async def send(self, conn: Connection) -> ClientResponse:
             resp = self.response_class(
                 self.method,
                 self.url,
-                writer=self._writer,  # type: ignore[arg-type]
+                writer=self._writer,
                 continue100=self._continue,
                 timer=self._timer,
                 request_info=self.request_info,

tests/test_client_response.py

@@ -300,7 +300,7 @@ async def test_response_eof(
         "get",
         URL("http://def-cl-resp.org"),
         request_info=mock.Mock(),
-        writer=None,  # type: ignore[arg-type]
+        writer=None,
         continue100=None,
         timer=TimerNoop(),
         traces=[],
@@ -346,7 +346,7 @@ async def test_response_eof_after_connection_detach(
         "get",
         URL("http://def-cl-resp.org"),
         request_info=mock.Mock(),
-        writer=None,  # type: ignore[arg-type]
+        writer=None,
         continue100=None,
         timer=TimerNoop(),
         traces=[],

tests/test_proxy.py

@@ -268,7 +268,7 @@ def test_proxy_server_hostname_default(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],
@@ -351,7 +351,7 @@ def test_proxy_server_hostname_override(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],
@@ -533,7 +533,7 @@ def test_https_connect(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],
@@ -615,7 +615,7 @@ def test_https_connect_certificate_error(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],
@@ -692,7 +692,7 @@ def test_https_connect_ssl_error(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],
@@ -767,7 +767,7 @@ def test_https_connect_http_proxy_error(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],
@@ -843,7 +843,7 @@ def test_https_connect_resp_start_error(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],
@@ -979,7 +979,7 @@ def test_https_connect_pass_ssl_context(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],
@@ -1072,7 +1072,7 @@ def test_https_auth(
             "get",
             URL("http://proxy.example.com"),
             request_info=mock.Mock(),
-            writer=None,  # type: ignore[arg-type]
+            writer=None,
             continue100=None,
             timer=TimerNoop(),
             traces=[],