Improve performance of WebSockets when there is no timeout (#8660)

Author: bdraco

CHANGES/8660.misc.rst

@@ -0,0 +1,3 @@
+Improved performance of :py:meth:`~aiohttp.ClientWebSocketResponse.receive` and :py:meth:`~aiohttp.web.WebSocketResponse.receive` when there is no timeout. -- by :user:`bdraco`.
+
+The timeout context manager is now avoided when there is no timeout as it accounted for up to 50% of the time spent in the :py:meth:`~aiohttp.ClientWebSocketResponse.receive` and :py:meth:`~aiohttp.web.WebSocketResponse.receive` methods.

aiohttp/client_ws.py

@@ -291,6 +291,8 @@ async def close(self, *, code: int = WSCloseCode.OK, message: bytes = b"") -> bo
             return False
 
     async def receive(self, timeout: Optional[float] = None) -> WSMessage:
+        receive_timeout = timeout or self._timeout.ws_receive
+
         while True:
             if self._waiting:
                 raise RuntimeError("Concurrent call to receive() is not allowed")
@@ -304,9 +306,14 @@ async def receive(self, timeout: Optional[float] = None) -> WSMessage:
             try:
                 self._waiting = True
                 try:
-                    async with async_timeout.timeout(
-                        timeout or self._timeout.ws_receive
-                    ):
+                    if receive_timeout:
+                        # Entering the context manager and creating
+                        # Timeout() object can take almost 50% of the
+                        # run time in this loop so we avoid it if
+                        # there is no read timeout.
+                        async with async_timeout.timeout(receive_timeout):
+                            msg = await self._reader.read()
+                    else:
                         msg = await self._reader.read()
                     self._reset_heartbeat()
                 finally:

aiohttp/web_ws.py

@@ -509,6 +509,7 @@ async def receive(self, timeout: Optional[float] = None) -> WSMessage:
 
         loop = self._loop
         assert loop is not None
+        receive_timeout = timeout or self._receive_timeout
         while True:
             if self._waiting:
                 raise RuntimeError("Concurrent call to receive() is not allowed")
@@ -524,7 +525,14 @@ async def receive(self, timeout: Optional[float] = None) -> WSMessage:
             try:
                 self._waiting = True
                 try:
-                    async with async_timeout.timeout(timeout or self._receive_timeout):
+                    if receive_timeout:
+                        # Entering the context manager and creating
+                        # Timeout() object can take almost 50% of the
+                        # run time in this loop so we avoid it if
+                        # there is no read timeout.
+                        async with async_timeout.timeout(receive_timeout):
+                            msg = await self._reader.read()
+                    else:
                         msg = await self._reader.read()
                     self._reset_heartbeat()
                 finally: