8000 bpo-38119: Fix shmem resource tracking by applio · Pull Request #15989 · python/cpython · GitHub
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bpo-38119: Fix shmem resource tracking #15989

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bpo-38119: Fix shmem resource tracking #15989

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d0789e2
Eliminated premature destruction of shared memory segments by resourc…
applio Sep 11, 2019
1c18262
Add test verifying shared memory available to other processes with ha…
applio Sep 11, 2019
f7ccd55
Add blurb.
applio Sep 11, 2019
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Eliminated premature destruction of shared memory segments by resourc… 
…e tracker.
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@applio
applio committed Sep 11, 2019
commit d0789e253a117df2c90778a38d17bf2e1c749ad8
8 changes: 0 additions & 8 deletions Lib/multiprocessing/managers.py
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Expand Up @@ -1309,14 +1309,6 @@ class SharedMemoryManager(BaseManager):
_Server = SharedMemoryServer

def __init__(self, *args, **kwargs):
if os.name == "posix":
# bpo-36867: Ensure the resource_tracker is running before
# launching the manager process, so that concurrent
# shared_memory manipulation both in the manager and in the
# current process does not create two resource_tracker
# processes.
from . import resource_tracker
resource_tracker.ensure_running()
BaseManager.__init__(self, *args, **kwargs)
util.debug(f"{self.__class__.__name__} created by pid {getpid()}")

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1 change: 0 additions & 1 deletion Lib/multiprocessing/resource_tracker.py
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Expand Up @@ -39,7 +39,6 @@

_CLEANUP_FUNCS.update({
'semaphore': _multiprocessing.sem_unlink,
'shared_memory': _posixshmem.shm_unlink,
})


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5 changes: 0 additions & 5 deletions Lib/multiprocessing/shared_memory.py
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Expand Up @@ -113,9 +113,6 @@ def __init__(self, name=None, create=False, size=0):
self.unlink()
raise

from .resource_tracker import register
register(self._name, "shared_memory")

else:

# Windows Named Shared Memory
Expand Down Expand Up @@ -234,9 +231,7 @@ def unlink(self):
called once (and only once) across all processes which have access
to the shared memory block."""
if _USE_POSIX and self._name:
from .resource_tracker import unregister
_posixshmem.shm_unlink(self._name)
unregister(self._name, "shared_memory")


_encoding = "utf8"
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43 changes: 0 additions & 43 deletions Lib/test/_test_multiprocessing.py
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Expand Up @@ -4012,49 +4012,6 @@ def test_shared_memory_ShareableList_pickling(self):
deserialized_sl.shm.close()
sl.shm.close()

def test_shared_memory_cleaned_after_process_termination(self):
cmd = '''if 1:
import os, time, sys
from multiprocessing import shared_memory

# Create a shared_memory segment, and send the segment name
sm = shared_memory.SharedMemory(create=True, size=10)
sys.stdout.write(sm.name + '\\n')
sys.stdout.flush()
time.sleep(100)
'''
with subprocess.Popen([sys.executable, '-E', '-c', cmd],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE) as p:
name = p.stdout.readline().strip().decode()

# killing abruptly processes holding reference to a shared memory
# segment should not leak the given memory segment.
p.terminate()
p.wait()

deadline = time.monotonic() + 60
t = 0.1
while time.monotonic() < deadline:
time.sleep(t)
t = min(t*2, 5)
try:
smm = shared_memory.SharedMemory(name, create=False)
except FileNotFoundError:
break
else:
raise AssertionError("A SharedMemory segment was leaked after"
" a process was abruptly terminated.")

if os.name == 'posix':
# A warning was emitted by the subprocess' own
# resource_tracker (on Windows, shared memory segments
# are released automatically by the OS).
err = p.stderr.read().decode()
self.assertIn(
"resource_tracker: There appear to be 1 leaked "
"shared_memory objects to clean up at shutdown", err)

#
#
#
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0