8000 bpo-45125: Improves pickling docs and tests for `shared_memory` by sobolevn · Pull Request #28294 · python/cpython · GitHub
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bpo-45125: Improves pickling docs and tests for shared_memory #28294

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Merged
merged 4 commits into from
Oct 1, 2021
Merged

bpo-45125: Improves pickling docs and tests for shared_memory #28294

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d4756a7
bpo-45125: Improves pickling docs and tests for `shared_memory`
sobolevn Sep 11, 2021
301df7e
Adds subTest for each pickle protocol
sobolevn Sep 11, 2021
1bb847c
Address review
sobolevn Oct 1, 2021
5de9e10
Pass protocol
sobolevn Oct 1, 2021
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Address review
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@sobolevn
sobolevn committed Oct 1, 2021
commit 1bb847c8b4f23d1f5ef6dd47d13a77e053a7de65
58 changes: 31 additions & 27 deletions Lib/test/_test_multiprocessing.py
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Expand Up @@ -3935,36 +3935,37 @@ def test_shared_memory_pickle_unpickle(self):

# Test pickling
pickled_sms = pickle.dumps(sms, protocol=proto)
self.assertNotIn(b'pickle', pickled_sms)

# Test unpickling
sms2 = pickle.loads(pickled_sms)
self.assertIsInstance(sms2, sms.__class__)
self.assertIsInstance(sms2, shared_memory.SharedMemory)
self.assertEqual(sms.name, sms2.name)
self.assertEqual(
bytes(sms.buf[0:6]), bytes(sms2.buf[0:6]), b'pickle')
self.assertEqual(bytes(sms.buf[0:6]), b'pickle')
self.assertEqual(bytes(sms2.buf[0:6]), b'pickle')

# Test that unpickled version is still the same SharedMemory
sms.buf[0:6] = b'newval'
self.assertEqual(
bytes(sms.buf[0:6]), bytes(sms2.buf[0:6]), b'newval')
self.assertEqual(bytes(sms.buf[0:6]), b'newval')
self.assertEqual(bytes(sms2.buf[0:6]), b'newval')

sms2.buf[0:6] = b'oldval'
self.assertEqual(
bytes(sms.buf[0:6]), bytes(sms2.buf[0:6]), b'oldval')
self.assertEqual(bytes(sms.buf[0:6]), b'oldval')
self.assertEqual(bytes(sms2.buf[0:6]), b'oldval')

def test_shared_memory_pickle_unpickle_dead_object(self):
sms = shared_memory.SharedMemory(create=True, size=512)
sms.buf[0:6] = b'pickle'
pickled_sms = pickle.dumps(sms)
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
with self.subTest(proto=proto):
sms = shared_memory.SharedMemory(create=True, size=512)
sms.buf[0:6] = b'pickle'
pickled_sms = pickle.dumps(sms)

# Now, we are going to kill the original object.
# So, unpickled one won't be able to attach to it.
sms.close()
sms.unlink()
# Now, we are going to kill the original object.
# So, unpickled one won't be able to attach to it.
sms.close()
sms.unlink()

with self.assertRaises(FileNotFoundError):
pickle.loads(pickled_sms)
with self.assertRaises(FileNotFoundError):
pickle.loads(pickled_sms)

def test_shared_memory_across_processes(self):
# bpo-40135: don't define shared memory block's name in case of
Expand Down Expand Up @@ -4194,11 +4195,12 @@ def test_shared_memory_ShareableList_pickling(self):
deserialized_sl, shared_memory.ShareableList)
self.assertEqual(deserialized_sl[-1], 9)
self.assertIsNot(sl, deserialized_sl)

deserialized_sl[4] = "changed"
self.assertEqual(sl[4], "changed")
sl[3] = "newvalue"
self.assertEqual(deserialized_sl[3], "newvalue")

# Verify data is not being put into the pickled representation.
name = 'a' * len(sl.shm.name)
larger_sl = shared_memory.ShareableList(range(400))
self.addCleanup(larger_sl.shm.unlink)
serialized_larger_sl = pickle.dumps(larger_sl, protocol=proto)
Expand All @@ -4209,16 +4211,18 @@ def test_shared_memory_ShareableList_pickling(self):
sl.shm.close()

def test_shared_memory_ShareableList_pickling_dead_object(self):
sl = shared_memory.ShareableList(range(10))
serialized_sl = pickle.dumps(sl)
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
with self.subTest(proto=proto):
sl = shared_memory.ShareableList(range(10))
serialized_sl = pickle.dumps(sl)

# Now, we are going to kill the original object.
# So, unpickled one won't be able to attach to it.
sl.shm.close()
sl.shm.unlink()
# Now, we are going to kill the original object.
# So, unpickled one won't be able to attach to it.
sl.shm.close()
sl.shm.unlink()

with self.assertRaises(FileNotFoundError):
pickle.loads(serialized_sl)
with self.assertRaises(FileNotFoundError):
pickle.loads(serialized_sl)

def test_shared_memory_cleaned_after_process_termination(self):
cmd = '''if 1:
Expand Down
0