gh-79012: Add asyncio chat server HOWTO #144604
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Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Doc/howto/asyncio-chat-server.rst
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| Common pitfalls | ||
| =============== |
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This section isn't really about the chat server. These are just common asyncio traps that would fit better in the tutorial or the reference docs.
- Explain concepts (start_server, StreamReader/StreamWriter) before code - Use asyncio.TaskGroup for concurrent broadcasting - Use contextlib.suppress instead of bare except/pass - Remove Python test client, keep only nc/telnet - Properly explain asyncio.timeout before showing usage - Move implementation notes to code comments - Remove Exercises and Common pitfalls sections - Reorder seealso links in asyncio.rst Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Doc/howto/asyncio-chat-server.rst
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| The :meth:`~asyncio.StreamWriter.write` method buffers data without sending | ||
| it immediately. Awaiting :meth:`~asyncio.StreamWriter.drain` flushes the | ||
| buffer and applies back-pressure if the client is slow to read. Similarly, | ||
| :meth:`~asyncio.StreamWriter.close` initiates shutdown, and awaiting | ||
| :meth:`~asyncio.StreamWriter.wait_closed` waits until the connection is | ||
| fully closed. |
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This should go above the example.
Doc/howto/asyncio-chat-server.rst
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| :: | ||
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| import asyncio | ||
| import contextlib | ||
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| connected_clients: dict[str, asyncio.StreamWriter] = {} | ||
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| async def broadcast(message, *, sender=None): | ||
| """Send a message to all connected clients except the sender.""" | ||
| async def send(writer): | ||
| with contextlib.suppress(ConnectionError): | ||
| writer.write(message.encode()) | ||
| await writer.drain() | ||
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This code is really large. We should introduce small concepts and explain things, and then finally show the complete example at the end.
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| async with server: | ||
| await server.serve_forever() |
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| writer.close() | ||
| await writer.wait_closed() |
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This needs to be explained too.
- Move write/drain and close/wait_closed explanations above the echo server example - Explain async with server, serve_forever, and asyncio.run - Break chat server into subsections: client tracking, broadcasting, then the complete example - Show broadcast function separately before the full listing Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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I have made the requested changes; please review again |
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Thanks for making the requested changes! : please review the changes made to this pull request. |
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Summary
Adds a focused HOWTO for building a TCP chat server with asyncio streams, as suggested by @ZeroIntensity in the review of #144594:
The guide progressively builds from an echo server to a full chat server:
start_server,StreamReader/StreamWriter, write/drain, close/wait_closed)asyncio.timeout, plus exercisesNo overlap with the existing Conceptual Overview — this is purely a practical, hands-on HOWTO.
Test plan
make -C Doc checkpassesmake -C Doc htmlpasses (no warnings)🤖 Generated with Claude Code
📚 Documentation preview 📚: https://cpython-previews--144604.org.readthedocs.build/