Multiprocessing Test Issue - Dangling Threads #6699

Summary

When running the test_multiprocessing_* suite, there are differences in test output that, while not impeding the tests, are output while running the suite, but are in CPython.

Details

After some tests are run, this warning pops up:
Warning -- Dangling threads: {<DummyProcess(Thread-181 (worker), stopped daemon 201)>, <DummyProcess(Thread-182 (worker), stopped daemon 202)>, <DummyProcess(Thread-183 (worker), stopped daemon 203)>, <Thread(Thread-184 (_handle_workers), stopped daemon 204)>, <Thread(Thread-185 (_handle_tasks), stopped daemon 205)>, <Thread(Thread-186 (_handle_results), stopped daemon 206)>}

These tests include but are not limited to:

• test.test_multiprocessing_fork.test_processes.WithProcessesTestValue.test_value
• test.test_multiprocessing_fork.test_processes.WithProcessesTestPool.test_wrapped_exception