test: close the listeners before terminating the event loop #35583

Whenever a test creates a new P2PInterface object a new listener is created inside NetworkThread.create_listen_server() by calling cls.network_event_loop.create_server().

These listeners are never closed which might result in:

2026-06-10T22:13:35.3934880Z Task was destroyed but it is pending!
2026-06-10T22:13:35.3936020Z task: <Task pending name='Task-54' coro=<BaseSelectorEventLoop._accept_connection2() done, defined at /opt/homebrew/Cellar/python@3.14/3.14.5/Frameworks/Python.framework/Versions/3.14/lib/python3.14/asyncio/selector_events.py:217> wait_for=<Future finished result=None>>

when the event loop is closed.

Fix that by closing the listeners.

Fixes: #35508

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35583.

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I can't reproduce the problem from #35508 locally, so I can't confirm 100% that this fixes it.

The reasoning is this - the error is coming from a Python asyncio listening server. We do not use those for the SOCKS5 proxy, but use them for the P2PInterface objects:

bitcoind --> SOCKS5 proxy --> P2PInterface

we collect the listeners in NetworkThread.listeners but only to check for duplicate listening addr:port and never close them. So, extend NetworkThread.close() to close all of them. This seems like a good hygiene anyway.

I managed to get a diff that reproduces this locally by monkey-patching _accept_connection2:

diff --git a/test/functional/test_framework/test_framework.py b/test/functional/test_framework/test_framework.py
index 64dcbfd7ec..16a0805c4b 100755
--- a/test/functional/test_framework/test_framework.py
+++ b/test/functional/test_framework/test_framework.py
@@ -7,6 +7,7 @@
 import configparser
 from enum import Enum
 import argparse
+import asyncio
 from datetime import datetime, timezone
 from importlib.util import find_spec
 import logging
@@ -18,6 +19,7 @@ import random
 import re
 import shutil
 import subprocess
+import socket
 import sys
 import tempfile
 import time
@@ -281,6 +283,21 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
             pdb.set_trace()
 
         self.log.debug('Closing down network thread')
+
+        loop = self.network_thread.network_event_loop
+        make_transport = type(loop)._make_socket_transport
+
+        async def slow_accept(self, protocol_factory, conn, extra, sslcontext=None, server=None, *a, **k):
+            transport = make_transport(self, conn, asyncio.Protocol(), extra=extra, server=server)
+            try:
+                await asyncio.sleep(2)
+            finally:
+                transport.close()
+        type(loop)._accept_connection2 = slow_accept
+
+        addr, port = next(iter(NetworkThread.listeners))
+        self._repro_sock = socket.create_connection((addr, port))
+        time.sleep(0.3)
         self.network_thread.close(timeout=self.options.timeout_factor * 10)
         if self.success == TestStatus.FAILED:
             self.log.info("Not stopping nodes as test failed. The dangling processes will be cleaned up later.")

Confirmed this triggers the error every run on master, and does not trigger on this PR. Note: this fix only works on python > 3.12.1, so will still break on previous releases. (but wait, do we run the private broadcast tests on that CI job?)

this fix only works on python > 3.12.1

Why?

so will still break on previous releases. (but wait, do we run the private broadcast tests on that CI job?)

test_runner.py is ran, so "yes". Note that the change in this PR is not private broadcast specific.

Converted to draft because this needs some more fiddling with.

this fix only works on python > 3.12.1

Why?

https://github.com/python/cpython/blob/3.12/Lib/asyncio/base_events.py#L390-L395

Sorry, should be >= 3.12.1.