Using PR 3138 of bpo-31234, I noticed that test_asyncio leaks dangling threads.

Tests which randomly leak threads:
---
test.test_asyncio.test_base_events.BaseEventLoopWithSelectorTests.test_create_connection_no_inet_pton
test.test_asyncio.test_base_events.BaseEventLoopWithSelectorTests.test_create_connection_service_name
test.test_asyncio.test_base_events.BaseEventLoopWithSelectorTests.test_create_connection_bluetooth
test.test_asyncio.test_base_events.BaseEventLoopWithSelectorTests.test_create_datagram_endpoint_no_addrinfo
test.test_asyncio.test_futures.DuckTests.test_wrap_future
test.test_asyncio.test_futures.CFutureTests.test_wrap_future
test.test_asyncio.test_futures.CFutureTests.test_wrap_future_use_global_loop
test.test_asyncio.test_futures.PyFutureTests.test_wrap_future
test.test_asyncio.test_futures.PyFutureTests.test_wrap_future_use_global_loop
test.test_asyncio.test_selector_events.BaseSelectorEventLoopTests.test_sock_connect_resolve_using_socket_params
test.test_asyncio.test_tasks.RunCoroutineThreadsafeTests.test_run_coroutine_threadsafe
test.test_asyncio.test_tasks.RunCoroutineThreadsafeTests.test_run_coroutine_threadsafe_with_timeout
test.test_asyncio.test_tasks.RunCoroutineThreadsafeTests.test_run_coroutine_threadsafe_task_cancelled
test.test_asyncio.test_tasks.RunCoroutineThreadsafeTests.test_run_coroutine_threadsafe_task_factory_exception
---

Write this list into "tests" and run "python3 -m test --matchfile=tests".


haypo@selma$ ./python -u -m test -v test_asyncio --matchfile=tests
== CPython 3.7.0a0 (heads/concurrent_futures:f277fa3, Aug 21 2017, 18:11:41) [GCC 6.4.1 20170727 (Red Hat 6.4.1-1)]
(...)
test_create_connection_bluetooth (test.test_asyncio.test_base_events.BaseEventLoopWithSelectorTests) ... ok
test_create_connection_no_inet_pton (test.test_asyncio.test_base_events.BaseEventLoopWithSelectorTests) ... Warning -- threading_cleanup() detected 4 leaked threads (count: 4, dangling: 5)
ok
test_create_connection_service_name (test.test_asyncio.test_base_events.BaseEventLoopWithSelectorTests) ... Warning -- threading_cleanup() detected 4 leaked threads (count: 4, dangling: 5)
ok
test_create_datagram_endpoint_no_addrinfo (test.test_asyncio.test_base_events.BaseEventLoopWithSelectorTests) ... Warning -- threading_cleanup() detected 1 leaked threads (count: 1, dangling: 2)
ok
test_wrap_future (test.test_asyncio.test_futures.CFutureTests) ... Warning -- threading_cleanup() detected 1 leaked threads (count: 1, dangling: 2)
ok
test_wrap_future_use_global_loop (test.test_asyncio.test_futures.CFutureTests) ... Warning -- threading_cleanup() detected 1 leaked threads (count: 1, dangling: 2)
ok
test_wrap_future (test.test_asyncio.test_futures.DuckTests) ... ok
test_wrap_future (test.test_asyncio.test_futures.PyFutureTests) ... Warning -- threading_cleanup() detected 1 leaked threads (count: 1, dangling: 2)
ok
test_wrap_future_use_global_loop (test.test_asyncio.test_futures.PyFutureTests) ... Warning -- threading_cleanup() detected 1 leaked threads (count: 1, dangling: 2)
ok
test_sock_connect_resolve_using_socket_params (test.test_asyncio.test_selector_events.BaseSelectorEventLoopTests) ... Warning -- threading_cleanup() detected 1 leaked threads (count: 1, dangling: 2)
ok
test_run_coroutine_threadsafe (test.test_asyncio.test_tasks.RunCoroutineThreadsafeTests)
Test coroutine submission from a thread to an event loop. ... ok
test_run_coroutine_threadsafe_task_cancelled (test.test_asyncio.test_tasks.RunCoroutineThreadsafeTests)
Test coroutine submission from a tread to an event loop ... ok
test_run_coroutine_threadsafe_task_factory_exception (test.test_asyncio.test_tasks.RunCoroutineThreadsafeTests)
Test coroutine submission from a tread to an event loop ... Warning -- threading_cleanup() detected 1 leaked threads (count: 1, dangling: 2)
ok
test_run_coroutine_threadsafe_with_timeout (test.test_asyncio.test_tasks.RunCoroutineThreadsafeTests)
Test coroutine submission from a thread to an event loop ... ok
(...)