diff --git a/Lib/multiprocessing/managers.py b/Lib/multiprocessing/managers.py
index 75b5150f821b1c..f7c30eb6dd103a 100644
--- a/Lib/multiprocessing/managers.py
+++ b/Lib/multiprocessing/managers.py
@@ -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()}")
diff --git a/Lib/multiprocessing/resource_tracker.py b/Lib/multiprocessing/resource_tracker.py
index 61a6dd66e72e67..fa20bfd1aca6d1 100644
--- a/Lib/multiprocessing/resource_tracker.py
+++ b/Lib/multiprocessing/resource_tracker.py
@@ -39,7 +39,6 @@
_CLEANUP_FUNCS.update({
'semaphore': _multiprocessing.sem_unlink,
- 'shared_memory': _posixshmem.shm_unlink,
})
diff --git a/Lib/multiprocessing/shared_memory.py b/Lib/multiprocessing/shared_memory.py
index 184e36704baaeb..ebc88858762e8c 100644
--- a/Lib/multiprocessing/shared_memory.py
+++ b/Lib/multiprocessing/shared_memory.py
@@ -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
@@ -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"
diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index c717d0aad2874b..0a5b93e49ffef5 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -3829,6 +3829,27 @@ def test_shared_memory_across_processes(self):
sms.close()
+ def test_shared_memory_across_independently_started_processes(self):
+ # A Process may not trigger the same exit path as an independently
+ # spawned process (for example, resource trackers on a separate
+ # process). This tests that independently created processes can
+ # indeed continue to access shared memory and that that shared
+ # memory persists at least so long as one of the processes with a
+ # handle on it is alive.
+ sms = shared_memory.SharedMemory('test04_indep', True, size=256)
+ self.addCleanup(sms.unlink)
+
+ prog = (
+ "from multiprocessing import shared_memory; "
+ "sms = shared_memory.SharedMemory('test04_indep'); "
+ "sms.buf[:4] = b'1234'; "
+ "sms.close()"
+ )
+ rc, out, err = test.support.script_helper.assert_python_ok('-c', prog)
+
+ self.assertFalse(err)
+ self.assertEqual(bytes(sms.buf[:4]), b'1234')
+
@unittest.skipIf(os.name != "posix", "not feasible in non-posix platforms")
def test_shared_memory_SharedMemoryServer_ignores_sigint(self):
# bpo-36368: protect SharedMemoryManager server process from
@@ -3853,27 +3874,6 @@ def test_shared_memory_SharedMemoryServer_ignores_sigint(self):
smm.shutdown()
- @unittest.skipIf(os.name != "posix", "resource_tracker is posix only")
- def test_shared_memory_SharedMemoryManager_reuses_resource_tracker(self):
- # bpo-36867: test that a SharedMemoryManager uses the
- # same resource_tracker process as its parent.
- cmd = '''if 1:
- from multiprocessing.managers import SharedMemoryManager
-
-
- smm = SharedMemoryManager()
- smm.start()
- sl = smm.ShareableList(range(10))
- smm.shutdown()
- '''
- rc, out, err = test.support.script_helper.assert_python_ok('-c', cmd)
-
- # Before bpo-36867 was fixed, a SharedMemoryManager not using the same
- # resource_tracker process as its parent would make the parent's
- # tracker complain about sl being leaked even though smm.shutdown()
- # properly released sl.
- self.assertFalse(err)
-
def test_shared_memory_SharedMemoryManager_basics(self):
smm1 = multiprocessing.managers.SharedMemoryManager()
with self.assertRaises(ValueError):
@@ -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)
-
#
#
#
@@ -5006,9 +4963,6 @@ def create_and_register_resource(rtype):
if rtype == "semaphore":
lock = mp.Lock()
return lock, lock._semlock.name
- elif rtype == "shared_memory":
- sm = SharedMemory(create=True, size=10)
- return sm, sm._name
else:
raise ValueError(
"Resource type {{}} not understood".format(rtype))
diff --git a/Misc/NEWS.d/next/Library/2019-09-11-11-08-53.bpo-38119.da_hwK.rst b/Misc/NEWS.d/next/Library/2019-09-11-11-08-53.bpo-38119.da_hwK.rst
new file mode 100644
index 00000000000000..5c29d4a2f36ca8
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-09-11-11-08-53.bpo-38119.da_hwK.rst
@@ -0,0 +1 @@
+Fix resource tracker treatment of shared memory as if it were a semaphore.
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