[3.12] gh-125679: multiprocessing Lock and RLock - fix invalid representation string on MacOSX. (GH-125680) (#126534)

gh-125679: multiprocessing Lock and RLock - fix invalid representation string on MacOSX. (GH-125680)
(cherry picked from commit 75f7cf9)

Co-authored-by: Duprat <[email protected]>

Author: miss-islington

Lib/multiprocessing/synchronize.py

@@ -174,7 +174,7 @@ def __repr__(self):
                 name = process.current_process().name
                 if threading.current_thread().name != 'MainThread':
                     name += '|' + threading.current_thread().name
-            elif self._semlock._get_value() == 1:
+            elif not self._semlock._is_zero():
                 name = 'None'
             elif self._semlock._count() > 0:
                 name = 'SomeOtherThread'
@@ -200,7 +200,7 @@ def __repr__(self):
                 if threading.current_thread().name != 'MainThread':
                     name += '|' + threading.current_thread().name
                 count = self._semlock._count()
-            elif self._semlock._get_value() == 1:
+            elif not self._semlock._is_zero():
                 name, count = 'None', 0
             elif self._semlock._count() > 0:
                 name, count = 'SomeOtherThread', 'nonzero'

Lib/test/_test_multiprocessing.py

@@ -1363,13 +1363,135 @@ def test_closed_queue_put_get_exceptions(self):
 
 class _TestLock(BaseTestCase):
 
+    @staticmethod
+    def _acquire(lock, l=None):
+        lock.acquire()
+        if l is not None:
+            l.append(repr(lock))
+
+    @staticmethod
+    def _acquire_event(lock, event):
+        lock.acquire()
+        event.set()
+        time.sleep(1.0)
+
+    def test_repr_lock(self):
+        if self.TYPE != 'processes':
+            self.skipTest('test not appropriate for {}'.format(self.TYPE))
+
+        lock = self.Lock()
+        self.assertEqual(f'<Lock(owner=None)>', repr(lock))
+
+        lock.acquire()
+        self.assertEqual(f'<Lock(owner=MainProcess)>', repr(lock))
+        lock.release()
+
+        tname = 'T1'
+        l = []
+        t = threading.Thread(target=self._acquire,
+                             args=(lock, l),
+                             name=tname)
+        t.start()
+        time.sleep(0.1)
+        self.assertEqual(f'<Lock(owner=MainProcess|{tname})>', l[0])
+        lock.release()
+
+        t = threading.Thread(target=self._acquire,
+                             args=(lock,),
+                             name=tname)
+        t.start()
+        time.sleep(0.1)
+        self.assertEqual('<Lock(owner=SomeOtherThread)>', repr(lock))
+        lock.release()
+
+        pname = 'P1'
+        l = multiprocessing.Manager().list()
+        p = self.Process(target=self._acquire,
+                         args=(lock, l),
+                         name=pname)
+        p.start()
+        p.join()
+        self.assertEqual(f'<Lock(owner={pname})>', l[0])
+
+        lock = self.Lock()
+        event = self.Event()
+        p = self.Process(target=self._acquire_event,
+                         args=(lock, event),
+                         name='P2')
+        p.start()
+        event.wait()
+        self.assertEqual(f'<Lock(owner=SomeOtherProcess)>', repr(lock))
+        p.terminate()
+
     def test_lock(self):
         lock = self.Lock()
         self.assertEqual(lock.acquire(), True)
         self.assertEqual(lock.acquire(False), False)
         self.assertEqual(lock.release(), None)
         self.assertRaises((ValueError, threading.ThreadError), lock.release)
 
+    @staticmethod
+    def _acquire_release(lock, timeout, l=None, n=1):
+        for _ in range(n):
+            lock.acquire()
+        if l is not None:
+            l.append(repr(lock))
+        time.sleep(timeout)
+        for _ in range(n):
+            lock.release()
+
+    def test_repr_rlock(self):
+        if self.TYPE != 'processes':
+            self.skipTest('test not appropriate for {}'.format(self.TYPE))
+
+        lock = self.RLock()
+        self.assertEqual('<RLock(None, 0)>', repr(lock))
+
+        n = 3
+        for _ in range(n):
+            lock.acquire()
+        self.assertEqual(f'<RLock(MainProcess, {n})>', repr(lock))
+        for _ in range(n):
+            lock.release()
+
+        t, l = [], []
+        for i in range(n):
+            t.append(threading.Thread(target=self._acquire_release,
+                                      args=(lock, 0.1, l, i+1),
+                                      name=f'T{i+1}'))
+            t[-1].start()
+        for t_ in t:
+            t_.join()
+        for i in range(n):
+            self.assertIn(f'<RLock(MainProcess|T{i+1}, {i+1})>', l)
+
+
+        t = threading.Thread(target=self._acquire_release,
+                                 args=(lock, 0.2),
+                                 name=f'T1')
+        t.start()
+        time.sleep(0.1)
+        self.assertEqual('<RLock(SomeOtherThread, nonzero)>', repr(lock))
+        time.sleep(0.2)
+
+        pname = 'P1'
+        l = multiprocessing.Manager().list()
+        p = self.Process(target=self._acquire_release,
+                         args=(lock, 0.1, l),
+                         name=pname)
+        p.start()
+        p.join()
+        self.assertEqual(f'<RLock({pname}, 1)>', l[0])
+
+        event = self.Event()
+        lock = self.RLock()
+        p = self.Process(target=self._acquire_event,
+                         args=(lock, event))
+        p.start()
+        event.wait()
+        self.assertEqual('<RLock(SomeOtherProcess, nonzero)>', repr(lock))
+        p.join()
+
     def test_rlock(self):
         lock = self.RLock()
         self.assertEqual(lock.acquire(), True)

Misc/NEWS.d/next/Library/2024-11-06-23-40-28.gh-issue-125679.Qq9xF5.rst

@@ -0,0 +1,2 @@
+The :class:`multiprocessing.Lock` and :class:`multiprocessing.RLock`
+``repr`` values no longer say "unknown" on macOS.