https://github.com/python/cpython/commit/1023dbbcb7f05e76053486ae7ef7f73b4cd... commit: 1023dbbcb7f05e76053486ae7ef7f73b4cdc5398 branch: master author: Antoine Pitrou <pitrou@free.fr> committer: GitHub <noreply@github.com> date: 2017-10-02T16:42:15+02:00 summary: bpo-31516: current_thread() should not return a dummy thread at shutdown (#3673) bpo-31516: current_thread() should not return a dummy thread at shutdown files: A Misc/NEWS.d/next/Library/2017-09-20-18-43-01.bpo-31516.23Yuq3.rst M Lib/test/test_threading.py M Lib/threading.py diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py index f7c3680bda3..6e1ae06f792 100644 --- a/Lib/test/test_threading.py +++ b/Lib/test/test_threading.py @@ -547,6 +547,35 @@ def f(): self.assertEqual(err, b"") self.assertEqual(data, "Thread-1\nTrue\nTrue\n") + def test_main_thread_during_shutdown(self): + # bpo-31516: current_thread() should still point to the main thread + # at shutdown + code = """if 1: + import gc, threading + + main_thread = threading.current_thread() + assert main_thread is threading.main_thread() # sanity check + + class RefCycle: + def __init__(self): + self.cycle = self + + def __del__(self): + print("GC:", + threading.current_thread() is main_thread, + threading.main_thread() is main_thread, + threading.enumerate() == [main_thread]) + + RefCycle() + gc.collect() # sanity check + x = RefCycle() + """ + _, out, err = assert_python_ok("-c", code) + data = out.decode() + self.assertEqual(err, b"") + self.assertEqual(data.splitlines(), + ["GC: True True True"] * 2) + def test_tstate_lock(self): # Test an implementation detail of Thread objects. started = _thread.allocate_lock() diff --git a/Lib/threading.py b/Lib/threading.py index e4bf974495b..418116faceb 100644 --- a/Lib/threading.py +++ b/Lib/threading.py @@ -1158,8 +1158,8 @@ def run(self): self.function(*self.args, **self.kwargs) self.finished.set() + # Special thread class to represent the main thread -# This is garbage collected through an exit handler class _MainThread(Thread): @@ -1272,7 +1272,6 @@ def _shutdown(): while t: t.join() t = _pickSomeNonDaemonThread() - _main_thread._delete() def _pickSomeNonDaemonThread(): for t in enumerate(): diff --git a/Misc/NEWS.d/next/Library/2017-09-20-18-43-01.bpo-31516.23Yuq3.rst b/Misc/NEWS.d/next/Library/2017-09-20-18-43-01.bpo-31516.23Yuq3.rst new file mode 100644 index 00000000000..af48d159fef --- /dev/null +++ b/Misc/NEWS.d/next/Library/2017-09-20-18-43-01.bpo-31516.23Yuq3.rst @@ -0,0 +1 @@ +``threading.current_thread()`` should not return a dummy thread at shutdown.