pythongh-131325: fix sendfile fallback implementation to drain data after writing to transport (python#131376)

kumaraditya303 · colesbury · commit 43125f31d89c · 2025-03-20T17:39:21.000Z
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
@@ -1295,8 +1295,8 @@ async def _sendfile_fallback(self, transp, file, offset, count):
                 read = await self.run_in_executor(None, file.readinto, view)
                 if not read:
                     return total_sent  # EOF
-                await proto.drain()
                 transp.write(view[:read])
+                await proto.drain()
                 total_sent += read
         finally:
             if total_sent > 0 and hasattr(file, 'seek'):
diff --git a/Misc/NEWS.d/next/Library/2025-03-17-18-50-39.gh-issue-131325.wlasMF.rst b/Misc/NEWS.d/next/Library/2025-03-17-18-50-39.gh-issue-131325.wlasMF.rst
@@ -0,0 +1 @@
+Fix sendfile fallback implementation to drain data after writing to transport in :mod:`asyncio`.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Fix sendfile fallback implementation to drain data after writing to transport in :mod:`asyncio`.