https://github.com/python/cpython/commit/f130b06da30616dd4dae363c7d8af79b540a7971 commit: f130b06da30616dd4dae363c7d8af79b540a7971 branch: 3.14 author: Petr Viktorin <[email protected]> committer: encukou <[email protected]> date: 2025-12-05T12:47:30+01:00 summary:
[3.14] gh-142206: multiprocessing.resource_tracker: Decode messages using older protocol (GH-142215) (GH-142285) (cherry picked from commit 4172644d78d58189e46424af0aea302b1d78e2de) Difference from the original commit: the default in 3.14 is to use the simpler original protocol (except for filenames with newlines). Co-authored-by: Petr Viktorin <[email protected]> files: A Misc/NEWS.d/next/Library/2025-12-03-09-36-29.gh-issue-142206.ilwegH.rst M Lib/multiprocessing/resource_tracker.py M Lib/test/_test_multiprocessing.py diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py index b0f9099f4a59f3..2ef2d1ece540d5 100644 --- a/Lib/multiprocessing/resource_tracker.py +++ b/Lib/multiprocessing/resource_tracker.py @@ -68,6 +68,13 @@ def __init__(self): self._exitcode = None self._reentrant_messages = deque() + # True to use colon-separated lines, rather than JSON lines, + # for internal communication. (Mainly for testing). + # Filenames not supported by the simple format will always be sent + # using JSON. + # The reader should understand all formats. + self._use_simple_format = True + def _reentrant_call_error(self): # gh-109629: this happens if an explicit call to the ResourceTracker # gets interrupted by a garbage collection, invoking a finalizer (*) @@ -200,7 +207,9 @@ def _launch(self): os.close(r) def _make_probe_message(self): - """Return a JSON-encoded probe message.""" + """Return a probe message.""" + if self._use_simple_format: + return b'PROBE:0:noop\n' return ( json.dumps( {"cmd": "PROBE", "rtype": "noop"}, @@ -267,6 +276,15 @@ def _write(self, msg): assert nbytes == len(msg), f"{nbytes=} != {len(msg)=}" def _send(self, cmd, name, rtype): + if self._use_simple_format and '\n' not in name: + msg = f"{cmd}:{name}:{rtype}\n".encode("ascii") + if len(msg) > 512: + # posix guarantees that writes to a pipe of less than PIPE_BUF + # bytes are atomic, and that PIPE_BUF >= 512 + raise ValueError('msg too long') + self._ensure_running_and_write(msg) + return + # POSIX guarantees that writes to a pipe of less than PIPE_BUF (512 on Linux) # bytes are atomic. Therefore, we want the message to be shorter than 512 bytes. # POSIX shm_open() and sem_open() require the name, including its leading slash, @@ -286,6 +304,7 @@ def _send(self, cmd, name, rtype): # The entire JSON message is guaranteed < PIPE_BUF (512 bytes) by construction. assert len(msg) <= 512, f"internal error: message too long ({len(msg)} bytes)" + assert msg.startswith(b'{') self._ensure_running_and_write(msg) @@ -296,6 +315,30 @@ def _send(self, cmd, name, rtype): getfd = _resource_tracker.getfd +def _decode_message(line): + if line.startswith(b'{'): + try: + obj = json.loads(line.decode('ascii')) + except Exception as e: + raise ValueError("malformed resource_tracker message: %r" % (line,)) from e + + cmd = obj["cmd"] + rtype = obj["rtype"] + b64 = obj.get("base64_name", "") + + if not isinstance(cmd, str) or not isinstance(rtype, str) or not isinstance(b64, str): + raise ValueError("malformed resource_tracker fields: %r" % (obj,)) + + try: + name = base64.urlsafe_b64decode(b64).decode('utf-8', 'surrogateescape') + except ValueError as e: + raise ValueError("malformed resource_tracker base64_name: %r" % (b64,)) from e + else: + cmd, rest = line.strip().decode('ascii').split(':', maxsplit=1) + name, rtype = rest.rsplit(':', maxsplit=1) + return cmd, rtype, name + + def main(fd): '''Run resource tracker.''' # protect the process from ^C and "killall python" etc @@ -318,23 +361,7 @@ def main(fd): with open(fd, 'rb') as f: for line in f: try: - try: - obj = json.loads(line.decode('ascii')) - except Exception as e: - raise ValueError("malformed resource_tracker message: %r" % (line,)) from e - - cmd = obj["cmd"] - rtype = obj["rtype"] - b64 = obj.get("base64_name", "") - - if not isinstance(cmd, str) or not isinstance(rtype, str) or not isinstance(b64, str): - raise ValueError("malformed resource_tracker fields: %r" % (obj,)) - - try: - name = base64.urlsafe_b64decode(b64).decode('utf-8', 'surrogateescape') - except ValueError as e: - raise ValueError("malformed resource_tracker base64_name: %r" % (b64,)) from e - + cmd, rtype, name = _decode_message(line) cleanup_func = _CLEANUP_FUNCS.get(rtype, None) if cleanup_func is None: raise ValueError( diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py index 1a188daa003b85..4b437f8eb48865 100644 --- a/Lib/test/_test_multiprocessing.py +++ b/Lib/test/_test_multiprocessing.py @@ -39,7 +39,7 @@ from test.support import socket_helper from test.support import threading_helper from test.support import warnings_helper - +from test.support import subTests # Skip tests if _multiprocessing wasn't built. _multiprocessing = import_helper.import_module('_multiprocessing') @@ -4284,6 +4284,19 @@ def test_copy(self): self.assertEqual(bar.z, 2 ** 33) +def resource_tracker_format_subtests(func): + """Run given test using both resource tracker communication formats""" + def _inner(self, *args, **kwargs): + tracker = resource_tracker._resource_tracker + for use_simple_format in False, True: + with ( + self.subTest(use_simple_format=use_simple_format), + unittest.mock.patch.object( + tracker, '_use_simple_format', use_simple_format) + ): + func(self, *args, **kwargs) + return _inner + @unittest.skipUnless(HAS_SHMEM, "requires multiprocessing.shared_memory") @hashlib_helper.requires_hashdigest('sha256') class _TestSharedMemory(BaseTestCase): @@ -4561,6 +4574,7 @@ def test_shared_memory_SharedMemoryServer_ignores_sigint(self): smm.shutdown() @unittest.skipIf(os.name != "posix", "resource_tracker is posix only") + @resource_tracker_format_subtests def test_shared_memory_SharedMemoryManager_reuses_resource_tracker(self): # bpo-36867: test that a SharedMemoryManager uses the # same resource_tracker process as its parent. @@ -4811,6 +4825,7 @@ def test_shared_memory_cleaned_after_process_termination(self): "shared_memory objects to clean up at shutdown", err) @unittest.skipIf(os.name != "posix", "resource_tracker is posix only") + @resource_tracker_format_subtests def test_shared_memory_untracking(self): # gh-82300: When a separate Python process accesses shared memory # with track=False, it must not cause the memory to be deleted @@ -4838,6 +4853,7 @@ def test_shared_memory_untracking(self): mem.close() @unittest.skipIf(os.name != "posix", "resource_tracker is posix only") + @resource_tracker_format_subtests def test_shared_memory_tracking(self): # gh-82300: When a separate Python process accesses shared memory # with track=True, it must cause the memory to be deleted when @@ -7149,13 +7165,18 @@ class SemLock(_multiprocessing.SemLock): @unittest.skipUnless(HAS_SHMEM, "requires multiprocessing.shared_memory") class TestSharedMemoryNames(unittest.TestCase): - def test_that_shared_memory_name_with_colons_has_no_resource_tracker_errors(self): + @subTests('use_simple_format', (True, False)) + def test_that_shared_memory_name_with_colons_has_no_resource_tracker_errors( + self, use_simple_format): # Test script that creates and cleans up shared memory with colon in name test_script = textwrap.dedent(""" import sys from multiprocessing import shared_memory + from multiprocessing import resource_tracker import time + resource_tracker._resource_tracker._use_simple_format = %s + # Test various patterns of colons in names test_names = [ "a:b", @@ -7183,7 +7204,7 @@ def test_that_shared_memory_name_with_colons_has_no_resource_tracker_errors(self sys.exit(1) print("SUCCESS") - """) + """ % use_simple_format) rc, out, err = script_helper.assert_python_ok("-c", test_script) self.assertIn(b"SUCCESS", out) diff --git a/Misc/NEWS.d/next/Library/2025-12-03-09-36-29.gh-issue-142206.ilwegH.rst b/Misc/NEWS.d/next/Library/2025-12-03-09-36-29.gh-issue-142206.ilwegH.rst new file mode 100644 index 00000000000000..2fc2e3098f8c25 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2025-12-03-09-36-29.gh-issue-142206.ilwegH.rst @@ -0,0 +1,7 @@ +The resource tracker in the :mod:`multiprocessing` module now uses the +original communication protocol, as in Python 3.14.0 and below, +by default. +This avoids issues with upgrading Python while it is running. +(Note that such 'in-place' upgrades are not tested.) +The tracker remains compatible with subprocesses that use new protocol +(that is, subprocesses using Python 3.13.10, 3.14.1 and 3.15). _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
