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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Abandoned StreamWriter isn't reliably detected","articleBody":"# Bug report\n\n### Bug description:\n\nA StreamWriter should be `close()`:d when you are done with it. There is code in the destructor for StreamWriter to detect when this is overlooked and trigger a `ResourceWarning`. However, the current code often maintains a strong reference to the writer, preventing it from being garbage collected and hence no warning.\n\nTest case:\n\n```python\n#!/usr/bin/python3\n\nimport asyncio\nimport gc\nimport socket\n\nasync def handle_echo(reader, writer):\n    addr = writer.get_extra_info('peername')\n    print(f\"Connection from {addr!r}\")\n    # Forgetting to close the writer\n    #writer.close()\n    #await writer.wait_closed()\n\nasync def main():\n    server = await asyncio.start_server(\n        handle_echo, '127.0.0.1', 8888)\n\n    addrs = ', '.join(str(sock.getsockname()) for sock in server.sockets)\n    print(f'Serving on {addrs}')\n\n    client = socket.create_connection(('127.0.0.1', 8888))\n    client.send(b'a' * 64 * 1024)\n\n    async with server:\n        for i in range(25):\n            await asyncio.sleep(0.1)\n            gc.collect()\n        print('Exiting')\n\n    print('Done serving')\n\n    client.close()\n\nasyncio.run(main())\n```\n\nTest case locks up waiting for the client connection, when instead I would expect a `ResourceWarning` and everything exiting nicely.\n\n### CPython versions tested on:\n\n3.12, CPython main branch\n\n### Operating systems tested on:\n\nLinux\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-115661\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/CendioOssman","@type":"Person","name":"CendioOssman"},"datePublished":"2024-02-02T15:03:50.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/114914/cpython/issues/114914"}