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Issue #18999: Make multiprocessing use context objects.

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This allows different parts of a program to use different methods for
starting processes without interfering with each other.
This commit is contained in:
Richard Oudkerk 2013-10-16 16:41:56 +01:00
parent 3e4b52875e
commit b1694cf588
20 changed files with 733 additions and 611 deletions
Download patch file Download diff file Expand all files Collapse all files

42
Lib/test/_test_multiprocessing.py
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@ -3555,6 +3555,32 @@ class TestIgnoreEINTR(unittest.TestCase):
conn.close()
class TestStartMethod(unittest.TestCase):
@classmethod
def _check_context(cls, conn):
conn.send(multiprocessing.get_start_method())
def check_context(self, ctx):
r, w = ctx.Pipe(duplex=False)
p = ctx.Process(target=self._check_context, args=(w,))
p.start()
w.close()
child_method = r.recv()
r.close()
p.join()
self.assertEqual(child_method, ctx.get_start_method())
def test_context(self):
for method in ('fork', 'spawn', 'forkserver'):
try:
ctx = multiprocessing.get_context(method)
except ValueError:
continue
self.assertEqual(ctx.get_start_method(), method)
self.assertIs(ctx.get_context(), ctx)
self.assertRaises(ValueError, ctx.set_start_method, 'spawn')
self.assertRaises(ValueError, ctx.set_start_method, None)
self.check_context(ctx)
def test_set_get(self):
multiprocessing.set_forkserver_preload(PRELOAD)
count = 0
@ -3562,13 +3588,19 @@ class TestStartMethod(unittest.TestCase):
try:
for method in ('fork', 'spawn', 'forkserver'):
try:
multiprocessing.set_start_method(method)
multiprocessing.set_start_method(method, force=True)
except ValueError:
continue
self.assertEqual(multiprocessing.get_start_method(), method)
ctx = multiprocessing.get_context()
self.assertEqual(ctx.get_start_method(), method)
self.assertTrue(type(ctx).__name__.lower().startswith(method))
self.assertTrue(
ctx.Process.__name__.lower().startswith(method))
self.check_context(multiprocessing)
count += 1
finally:
multiprocessing.set_start_method(old_method)
multiprocessing.set_start_method(old_method, force=True)
self.assertGreaterEqual(count, 1)
def test_get_all(self):
@ -3753,9 +3785,9 @@ def install_tests_in_module_dict(remote_globs, start_method):
multiprocessing.process._cleanup()
dangling[0] = multiprocessing.process._dangling.copy()
dangling[1] = threading._dangling.copy()
old_start_method[0] = multiprocessing.get_start_method()
old_start_method[0] = multiprocessing.get_start_method(allow_none=True)
try:
multiprocessing.set_start_method(start_method)
multiprocessing.set_start_method(start_method, force=True)
except ValueError:
raise unittest.SkipTest(start_method +
' start method not supported')
@ -3771,7 +3803,7 @@ def install_tests_in_module_dict(remote_globs, start_method):
multiprocessing.get_logger().setLevel(LOG_LEVEL)
def tearDownModule():
multiprocessing.set_start_method(old_start_method[0])
multiprocessing.set_start_method(old_start_method[0], force=True)
# pause a bit so we don't get warning about dangling threads/processes
time.sleep(0.5)
multiprocessing.process._cleanup()