diff options
| -rw-r--r-- | Lib/multiprocessing/synchronize.py | 8 | ||||
| -rw-r--r-- | Lib/test/_test_multiprocessing.py | 26 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Core and Builtins/2023-08-30-15-41-47.gh-issue-108520.u0ZGP_.rst | 3 |
3 files changed, 34 insertions, 3 deletions
diff --git a/Lib/multiprocessing/synchronize.py b/Lib/multiprocessing/synchronize.py index 2328d33..3ccbfe3 100644 --- a/Lib/multiprocessing/synchronize.py +++ b/Lib/multiprocessing/synchronize.py @@ -50,8 +50,8 @@ class SemLock(object): def __init__(self, kind, value, maxvalue, *, ctx): if ctx is None: ctx = context._default_context.get_context() - self.is_fork_ctx = ctx.get_start_method() == 'fork' - unlink_now = sys.platform == 'win32' or self.is_fork_ctx + self._is_fork_ctx = ctx.get_start_method() == 'fork' + unlink_now = sys.platform == 'win32' or self._is_fork_ctx for i in range(100): try: sl = self._semlock = _multiprocessing.SemLock( @@ -103,7 +103,7 @@ class SemLock(object): if sys.platform == 'win32': h = context.get_spawning_popen().duplicate_for_child(sl.handle) else: - if self.is_fork_ctx: + if self._is_fork_ctx: raise RuntimeError('A SemLock created in a fork context is being ' 'shared with a process in a spawn context. This is ' 'not supported. Please use the same context to create ' @@ -115,6 +115,8 @@ class SemLock(object): self._semlock = _multiprocessing.SemLock._rebuild(*state) util.debug('recreated blocker with handle %r' % state[0]) self._make_methods() + # Ensure that deserialized SemLock can be serialized again (gh-108520). + self._is_fork_ctx = False @staticmethod def _make_name(): diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py index 9bc8242..3476371 100644 --- a/Lib/test/_test_multiprocessing.py +++ b/Lib/test/_test_multiprocessing.py @@ -5367,6 +5367,32 @@ class TestStartMethod(unittest.TestCase): p.start() p.join() + @classmethod + def _put_one_in_queue(cls, queue): + queue.put(1) + + @classmethod + def _put_two_and_nest_once(cls, queue): + queue.put(2) + process = multiprocessing.Process(target=cls._put_one_in_queue, args=(queue,)) + process.start() + process.join() + + def test_nested_startmethod(self): + # gh-108520: Regression test to ensure that child process can send its + # arguments to another process + queue = multiprocessing.Queue() + + process = multiprocessing.Process(target=self._put_two_and_nest_once, args=(queue,)) + process.start() + process.join() + + results = [] + while not queue.empty(): + results.append(queue.get()) + + self.assertEqual(results, [2, 1]) + @unittest.skipIf(sys.platform == "win32", "test semantics don't make sense on Windows") diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-08-30-15-41-47.gh-issue-108520.u0ZGP_.rst b/Misc/NEWS.d/next/Core and Builtins/2023-08-30-15-41-47.gh-issue-108520.u0ZGP_.rst new file mode 100644 index 0000000..44131fb --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2023-08-30-15-41-47.gh-issue-108520.u0ZGP_.rst @@ -0,0 +1,3 @@ +Fix :meth:`multiprocessing.synchronize.SemLock.__setstate__` to properly initialize :attr:`multiprocessing.synchronize.SemLock._is_fork_ctx`. This fixes a regression when passing a SemLock accross nested processes.
+
+Rename :attr:`multiprocessing.synchronize.SemLock.is_fork_ctx` to :attr:`multiprocessing.synchronize.SemLock._is_fork_ctx` to avoid exposing it as public API.
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