René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Calling SelectorSocketTransport.writelines with a very large payload doesn't get completely written to the socket","articleBody":"# Bug report\r\n\r\nAs a consequence of the optimization introduced in #91166, when `SelectorSocketTransport.writelines` is used with a very large buffer which can't be written in one shot either by using `socket.send` or `socket.sendmsg` the remaining data in the buffer is never written to the socket. \r\n\r\nThe following example can be used to reproduce the error:\r\n\r\n```python\r\nimport asyncio\r\n\r\n\r\nasync def send_message(chunk_size: int, chunks: int):\r\n    await asyncio.sleep(1)\r\n    reader, writer = await asyncio.open_connection(\"127.0.0.1\", 9898)\r\n    data = [bytes(chunk_size)] * chunks + [b\"end\"]\r\n    writer.writelines(data)\r\n    await writer.drain()\r\n    writer.close()\r\n    await writer.wait_closed()\r\n\r\n\r\nasync def handle_message(reader, writer):\r\n    data = await reader.read()\r\n    print(f\"End marker: {data[-3:]!r}\")\r\n    writer.close()\r\n    await writer.wait_closed()\r\n\r\n\r\nasync def run_server():\r\n    server = await asyncio.start_server(handle_message, \"127.0.0.1\", 9898)\r\n    async with server:\r\n        await server.serve_forever()\r\n\r\n\r\nasync def main():\r\n    await asyncio.gather(run_server(), send_message(6500, 100))\r\n\r\n\r\nasyncio.run(main())\r\n```\r\n\r\nThe example above prints `End marker: b'end'` with python 3.11 but not with python `3.12.0a6+`\r\n\r\n# Your environment\r\n\r\n- CPython versions tested on: `3.12.0a7`\r\n- Operating system and architecture: macOS 13.2\r\n\r\n\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-103463\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/alisaifee","@type":"Person","name":"alisaifee"},"datePublished":"2023-04-12T02:00:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/103462/cpython/issues/103462"}