[PR #9031/9f0ae074 backport][3.10] Avoid tracing overhead in http_wri…

…ter when there are no traces (#9045)

Co-authored-by: J. Nick Koston <nick@koston.org>

CHANGES/9031.misc.rst

@@ -0,0 +1 @@
+Tracing overhead is avoided in the http writer when there are no active traces -- by user:`bdraco`.

aiohttp/client_reqrep.py

@@ -696,11 +696,15 @@ async def send(self, conn: "Connection") -> "ClientResponse":
         writer = StreamWriter(
             protocol,
             self.loop,
-            on_chunk_sent=functools.partial(
-                self._on_chunk_request_sent, self.method, self.url
+            on_chunk_sent=(
+                functools.partial(self._on_chunk_request_sent, self.method, self.url)
+                if self._traces
+                else None
             ),
-            on_headers_sent=functools.partial(
-                self._on_headers_request_sent, self.method, self.url
+            on_headers_sent=(
+                functools.partial(self._on_headers_request_sent, self.method, self.url)
+                if self._traces
+                else None
             ),
         )