1016 lines
33 KiB
Python
1016 lines
33 KiB
Python
import unittest
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from test.support import (verbose, refcount_test, run_unittest,
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strip_python_stderr, cpython_only)
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from test.script_helper import assert_python_ok, make_script, temp_dir
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import sys
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import time
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import gc
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import weakref
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try:
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import threading
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except ImportError:
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threading = None
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try:
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from _testcapi import with_tp_del
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except ImportError:
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def with_tp_del(cls):
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class C(object):
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def __new__(cls, *args, **kwargs):
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raise TypeError('requires _testcapi.with_tp_del')
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return C
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### Support code
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###############################################################################
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# Bug 1055820 has several tests of longstanding bugs involving weakrefs and
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# cyclic gc.
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# An instance of C1055820 has a self-loop, so becomes cyclic trash when
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# unreachable.
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class C1055820(object):
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def __init__(self, i):
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self.i = i
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self.loop = self
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class GC_Detector(object):
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# Create an instance I. Then gc hasn't happened again so long as
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# I.gc_happened is false.
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def __init__(self):
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self.gc_happened = False
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def it_happened(ignored):
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self.gc_happened = True
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# Create a piece of cyclic trash that triggers it_happened when
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# gc collects it.
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self.wr = weakref.ref(C1055820(666), it_happened)
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@with_tp_del
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class Uncollectable(object):
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"""Create a reference cycle with multiple __del__ methods.
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An object in a reference cycle will never have zero references,
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and so must be garbage collected. If one or more objects in the
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cycle have __del__ methods, the gc refuses to guess an order,
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and leaves the cycle uncollected."""
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def __init__(self, partner=None):
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if partner is None:
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self.partner = Uncollectable(partner=self)
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else:
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self.partner = partner
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def __tp_del__(self):
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pass
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### Tests
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###############################################################################
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class GCTests(unittest.TestCase):
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def test_list(self):
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l = []
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l.append(l)
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gc.collect()
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del l
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self.assertEqual(gc.collect(), 1)
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def test_dict(self):
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d = {}
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d[1] = d
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gc.collect()
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del d
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self.assertEqual(gc.collect(), 1)
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def test_tuple(self):
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# since tuples are immutable we close the loop with a list
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l = []
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t = (l,)
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l.append(t)
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gc.collect()
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del t
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del l
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self.assertEqual(gc.collect(), 2)
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def test_class(self):
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class A:
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pass
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A.a = A
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gc.collect()
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del A
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self.assertNotEqual(gc.collect(), 0)
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def test_newstyleclass(self):
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class A(object):
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pass
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gc.collect()
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del A
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self.assertNotEqual(gc.collect(), 0)
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def test_instance(self):
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class A:
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pass
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a = A()
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a.a = a
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gc.collect()
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del a
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self.assertNotEqual(gc.collect(), 0)
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def test_newinstance(self):
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class A(object):
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pass
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a = A()
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a.a = a
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gc.collect()
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del a
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self.assertNotEqual(gc.collect(), 0)
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class B(list):
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pass
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class C(B, A):
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pass
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a = C()
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a.a = a
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gc.collect()
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del a
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self.assertNotEqual(gc.collect(), 0)
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del B, C
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self.assertNotEqual(gc.collect(), 0)
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A.a = A()
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del A
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self.assertNotEqual(gc.collect(), 0)
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self.assertEqual(gc.collect(), 0)
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def test_method(self):
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# Tricky: self.__init__ is a bound method, it references the instance.
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class A:
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def __init__(self):
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self.init = self.__init__
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a = A()
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gc.collect()
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del a
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self.assertNotEqual(gc.collect(), 0)
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@cpython_only
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def test_legacy_finalizer(self):
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# A() is uncollectable if it is part of a cycle, make sure it shows up
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# in gc.garbage.
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@with_tp_del
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class A:
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def __tp_del__(self): pass
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class B:
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pass
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a = A()
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a.a = a
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id_a = id(a)
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b = B()
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b.b = b
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gc.collect()
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del a
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del b
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self.assertNotEqual(gc.collect(), 0)
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for obj in gc.garbage:
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if id(obj) == id_a:
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del obj.a
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break
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else:
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self.fail("didn't find obj in garbage (finalizer)")
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gc.garbage.remove(obj)
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@cpython_only
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def test_legacy_finalizer_newclass(self):
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# A() is uncollectable if it is part of a cycle, make sure it shows up
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# in gc.garbage.
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@with_tp_del
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class A(object):
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def __tp_del__(self): pass
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class B(object):
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pass
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a = A()
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a.a = a
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id_a = id(a)
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b = B()
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b.b = b
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gc.collect()
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del a
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del b
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self.assertNotEqual(gc.collect(), 0)
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for obj in gc.garbage:
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if id(obj) == id_a:
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del obj.a
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break
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else:
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self.fail("didn't find obj in garbage (finalizer)")
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gc.garbage.remove(obj)
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def test_function(self):
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# Tricky: f -> d -> f, code should call d.clear() after the exec to
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# break the cycle.
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d = {}
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exec("def f(): pass\n", d)
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gc.collect()
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del d
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self.assertEqual(gc.collect(), 2)
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@refcount_test
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def test_frame(self):
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def f():
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frame = sys._getframe()
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gc.collect()
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f()
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self.assertEqual(gc.collect(), 1)
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def test_saveall(self):
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# Verify that cyclic garbage like lists show up in gc.garbage if the
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# SAVEALL option is enabled.
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# First make sure we don't save away other stuff that just happens to
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# be waiting for collection.
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gc.collect()
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# if this fails, someone else created immortal trash
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self.assertEqual(gc.garbage, [])
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L = []
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L.append(L)
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id_L = id(L)
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debug = gc.get_debug()
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gc.set_debug(debug | gc.DEBUG_SAVEALL)
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del L
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gc.collect()
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gc.set_debug(debug)
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self.assertEqual(len(gc.garbage), 1)
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obj = gc.garbage.pop()
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self.assertEqual(id(obj), id_L)
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def test_del(self):
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# __del__ methods can trigger collection, make this to happen
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thresholds = gc.get_threshold()
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gc.enable()
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gc.set_threshold(1)
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class A:
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def __del__(self):
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dir(self)
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a = A()
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del a
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gc.disable()
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gc.set_threshold(*thresholds)
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def test_del_newclass(self):
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# __del__ methods can trigger collection, make this to happen
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thresholds = gc.get_threshold()
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gc.enable()
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gc.set_threshold(1)
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class A(object):
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def __del__(self):
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dir(self)
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a = A()
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del a
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gc.disable()
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gc.set_threshold(*thresholds)
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# The following two tests are fragile:
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# They precisely count the number of allocations,
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# which is highly implementation-dependent.
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# For example, disposed tuples are not freed, but reused.
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# To minimize variations, though, we first store the get_count() results
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# and check them at the end.
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@refcount_test
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def test_get_count(self):
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gc.collect()
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a, b, c = gc.get_count()
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x = []
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d, e, f = gc.get_count()
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self.assertEqual((b, c), (0, 0))
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self.assertEqual((e, f), (0, 0))
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# This is less fragile than asserting that a equals 0.
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self.assertLess(a, 5)
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# Between the two calls to get_count(), at least one object was
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# created (the list).
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self.assertGreater(d, a)
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@refcount_test
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def test_collect_generations(self):
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gc.collect()
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# This object will "trickle" into generation N + 1 after
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# each call to collect(N)
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x = []
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gc.collect(0)
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# x is now in gen 1
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a, b, c = gc.get_count()
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gc.collect(1)
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# x is now in gen 2
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d, e, f = gc.get_count()
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gc.collect(2)
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# x is now in gen 3
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g, h, i = gc.get_count()
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# We don't check a, d, g since their exact values depends on
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# internal implementation details of the interpreter.
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self.assertEqual((b, c), (1, 0))
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self.assertEqual((e, f), (0, 1))
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self.assertEqual((h, i), (0, 0))
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def test_trashcan(self):
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class Ouch:
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n = 0
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def __del__(self):
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Ouch.n = Ouch.n + 1
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if Ouch.n % 17 == 0:
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gc.collect()
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# "trashcan" is a hack to prevent stack overflow when deallocating
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# very deeply nested tuples etc. It works in part by abusing the
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# type pointer and refcount fields, and that can yield horrible
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# problems when gc tries to traverse the structures.
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# If this test fails (as it does in 2.0, 2.1 and 2.2), it will
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# most likely die via segfault.
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# Note: In 2.3 the possibility for compiling without cyclic gc was
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# removed, and that in turn allows the trashcan mechanism to work
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# via much simpler means (e.g., it never abuses the type pointer or
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# refcount fields anymore). Since it's much less likely to cause a
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# problem now, the various constants in this expensive (we force a lot
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# of full collections) test are cut back from the 2.2 version.
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gc.enable()
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N = 150
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for count in range(2):
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t = []
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for i in range(N):
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t = [t, Ouch()]
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u = []
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for i in range(N):
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u = [u, Ouch()]
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v = {}
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for i in range(N):
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v = {1: v, 2: Ouch()}
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gc.disable()
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@unittest.skipUnless(threading, "test meaningless on builds without threads")
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def test_trashcan_threads(self):
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# Issue #13992: trashcan mechanism should be thread-safe
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NESTING = 60
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N_THREADS = 2
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def sleeper_gen():
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"""A generator that releases the GIL when closed or dealloc'ed."""
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try:
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yield
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finally:
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time.sleep(0.000001)
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class C(list):
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# Appending to a list is atomic, which avoids the use of a lock.
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inits = []
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dels = []
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def __init__(self, alist):
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self[:] = alist
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C.inits.append(None)
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def __del__(self):
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# This __del__ is called by subtype_dealloc().
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C.dels.append(None)
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# `g` will release the GIL when garbage-collected. This
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# helps assert subtype_dealloc's behaviour when threads
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# switch in the middle of it.
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g = sleeper_gen()
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next(g)
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# Now that __del__ is finished, subtype_dealloc will proceed
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# to call list_dealloc, which also uses the trashcan mechanism.
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def make_nested():
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"""Create a sufficiently nested container object so that the
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trashcan mechanism is invoked when deallocating it."""
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x = C([])
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for i in range(NESTING):
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x = [C([x])]
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del x
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def run_thread():
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"""Exercise make_nested() in a loop."""
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while not exit:
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make_nested()
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old_switchinterval = sys.getswitchinterval()
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sys.setswitchinterval(1e-5)
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try:
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exit = False
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threads = []
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for i in range(N_THREADS):
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t = threading.Thread(target=run_thread)
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threads.append(t)
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try:
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for t in threads:
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t.start()
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finally:
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time.sleep(1.0)
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exit = True
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for t in threads:
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t.join()
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finally:
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sys.setswitchinterval(old_switchinterval)
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gc.collect()
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self.assertEqual(len(C.inits), len(C.dels))
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def test_boom(self):
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class Boom:
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def __getattr__(self, someattribute):
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del self.attr
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raise AttributeError
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a = Boom()
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b = Boom()
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a.attr = b
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b.attr = a
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gc.collect()
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garbagelen = len(gc.garbage)
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del a, b
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# a<->b are in a trash cycle now. Collection will invoke
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# Boom.__getattr__ (to see whether a and b have __del__ methods), and
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# __getattr__ deletes the internal "attr" attributes as a side effect.
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# That causes the trash cycle to get reclaimed via refcounts falling to
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# 0, thus mutating the trash graph as a side effect of merely asking
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# whether __del__ exists. This used to (before 2.3b1) crash Python.
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# Now __getattr__ isn't called.
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self.assertEqual(gc.collect(), 4)
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self.assertEqual(len(gc.garbage), garbagelen)
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def test_boom2(self):
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class Boom2:
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def __init__(self):
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self.x = 0
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def __getattr__(self, someattribute):
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self.x += 1
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if self.x > 1:
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del self.attr
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raise AttributeError
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a = Boom2()
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b = Boom2()
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a.attr = b
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b.attr = a
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gc.collect()
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garbagelen = len(gc.garbage)
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del a, b
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# Much like test_boom(), except that __getattr__ doesn't break the
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# cycle until the second time gc checks for __del__. As of 2.3b1,
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# there isn't a second time, so this simply cleans up the trash cycle.
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# We expect a, b, a.__dict__ and b.__dict__ (4 objects) to get
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# reclaimed this way.
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self.assertEqual(gc.collect(), 4)
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self.assertEqual(len(gc.garbage), garbagelen)
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def test_boom_new(self):
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# boom__new and boom2_new are exactly like boom and boom2, except use
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# new-style classes.
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class Boom_New(object):
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def __getattr__(self, someattribute):
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del self.attr
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raise AttributeError
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a = Boom_New()
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b = Boom_New()
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a.attr = b
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b.attr = a
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gc.collect()
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garbagelen = len(gc.garbage)
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del a, b
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self.assertEqual(gc.collect(), 4)
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self.assertEqual(len(gc.garbage), garbagelen)
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def test_boom2_new(self):
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class Boom2_New(object):
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def __init__(self):
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self.x = 0
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def __getattr__(self, someattribute):
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self.x += 1
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if self.x > 1:
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del self.attr
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raise AttributeError
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a = Boom2_New()
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b = Boom2_New()
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a.attr = b
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b.attr = a
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gc.collect()
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garbagelen = len(gc.garbage)
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del a, b
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self.assertEqual(gc.collect(), 4)
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self.assertEqual(len(gc.garbage), garbagelen)
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def test_get_referents(self):
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alist = [1, 3, 5]
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got = gc.get_referents(alist)
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got.sort()
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self.assertEqual(got, alist)
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atuple = tuple(alist)
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got = gc.get_referents(atuple)
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got.sort()
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self.assertEqual(got, alist)
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adict = {1: 3, 5: 7}
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expected = [1, 3, 5, 7]
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got = gc.get_referents(adict)
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got.sort()
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self.assertEqual(got, expected)
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got = gc.get_referents([1, 2], {3: 4}, (0, 0, 0))
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got.sort()
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self.assertEqual(got, [0, 0] + list(range(5)))
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self.assertEqual(gc.get_referents(1, 'a', 4j), [])
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def test_is_tracked(self):
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# Atomic built-in types are not tracked, user-defined objects and
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# mutable containers are.
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# NOTE: types with special optimizations (e.g. tuple) have tests
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# in their own test files instead.
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self.assertFalse(gc.is_tracked(None))
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self.assertFalse(gc.is_tracked(1))
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self.assertFalse(gc.is_tracked(1.0))
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self.assertFalse(gc.is_tracked(1.0 + 5.0j))
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self.assertFalse(gc.is_tracked(True))
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self.assertFalse(gc.is_tracked(False))
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self.assertFalse(gc.is_tracked(b"a"))
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self.assertFalse(gc.is_tracked("a"))
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self.assertFalse(gc.is_tracked(bytearray(b"a")))
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self.assertFalse(gc.is_tracked(type))
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self.assertFalse(gc.is_tracked(int))
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self.assertFalse(gc.is_tracked(object))
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|
self.assertFalse(gc.is_tracked(object()))
|
|
|
|
class UserClass:
|
|
pass
|
|
self.assertTrue(gc.is_tracked(gc))
|
|
self.assertTrue(gc.is_tracked(UserClass))
|
|
self.assertTrue(gc.is_tracked(UserClass()))
|
|
self.assertTrue(gc.is_tracked([]))
|
|
self.assertTrue(gc.is_tracked(set()))
|
|
|
|
def test_bug1055820b(self):
|
|
# Corresponds to temp2b.py in the bug report.
|
|
|
|
ouch = []
|
|
def callback(ignored):
|
|
ouch[:] = [wr() for wr in WRs]
|
|
|
|
Cs = [C1055820(i) for i in range(2)]
|
|
WRs = [weakref.ref(c, callback) for c in Cs]
|
|
c = None
|
|
|
|
gc.collect()
|
|
self.assertEqual(len(ouch), 0)
|
|
# Make the two instances trash, and collect again. The bug was that
|
|
# the callback materialized a strong reference to an instance, but gc
|
|
# cleared the instance's dict anyway.
|
|
Cs = None
|
|
gc.collect()
|
|
self.assertEqual(len(ouch), 2) # else the callbacks didn't run
|
|
for x in ouch:
|
|
# If the callback resurrected one of these guys, the instance
|
|
# would be damaged, with an empty __dict__.
|
|
self.assertEqual(x, None)
|
|
|
|
def test_bug21435(self):
|
|
# This is a poor test - its only virtue is that it happened to
|
|
# segfault on Tim's Windows box before the patch for 21435 was
|
|
# applied. That's a nasty bug relying on specific pieces of cyclic
|
|
# trash appearing in exactly the right order in finalize_garbage()'s
|
|
# input list.
|
|
# But there's no reliable way to force that order from Python code,
|
|
# so over time chances are good this test won't really be testing much
|
|
# of anything anymore. Still, if it blows up, there's _some_
|
|
# problem ;-)
|
|
gc.collect()
|
|
|
|
class A:
|
|
pass
|
|
|
|
class B:
|
|
def __init__(self, x):
|
|
self.x = x
|
|
|
|
def __del__(self):
|
|
self.attr = None
|
|
|
|
def do_work():
|
|
a = A()
|
|
b = B(A())
|
|
|
|
a.attr = b
|
|
b.attr = a
|
|
|
|
do_work()
|
|
gc.collect() # this blows up (bad C pointer) when it fails
|
|
|
|
@cpython_only
|
|
def test_garbage_at_shutdown(self):
|
|
import subprocess
|
|
code = """if 1:
|
|
import gc
|
|
import _testcapi
|
|
@_testcapi.with_tp_del
|
|
class X:
|
|
def __init__(self, name):
|
|
self.name = name
|
|
def __repr__(self):
|
|
return "<X %%r>" %% self.name
|
|
def __tp_del__(self):
|
|
pass
|
|
|
|
x = X('first')
|
|
x.x = x
|
|
x.y = X('second')
|
|
del x
|
|
gc.set_debug(%s)
|
|
"""
|
|
def run_command(code):
|
|
p = subprocess.Popen([sys.executable, "-Wd", "-c", code],
|
|
stdout=subprocess.PIPE,
|
|
stderr=subprocess.PIPE)
|
|
stdout, stderr = p.communicate()
|
|
p.stdout.close()
|
|
p.stderr.close()
|
|
self.assertEqual(p.returncode, 0)
|
|
self.assertEqual(stdout.strip(), b"")
|
|
return strip_python_stderr(stderr)
|
|
|
|
stderr = run_command(code % "0")
|
|
self.assertIn(b"ResourceWarning: gc: 2 uncollectable objects at "
|
|
b"shutdown; use", stderr)
|
|
self.assertNotIn(b"<X 'first'>", stderr)
|
|
# With DEBUG_UNCOLLECTABLE, the garbage list gets printed
|
|
stderr = run_command(code % "gc.DEBUG_UNCOLLECTABLE")
|
|
self.assertIn(b"ResourceWarning: gc: 2 uncollectable objects at "
|
|
b"shutdown", stderr)
|
|
self.assertTrue(
|
|
(b"[<X 'first'>, <X 'second'>]" in stderr) or
|
|
(b"[<X 'second'>, <X 'first'>]" in stderr), stderr)
|
|
# With DEBUG_SAVEALL, no additional message should get printed
|
|
# (because gc.garbage also contains normally reclaimable cyclic
|
|
# references, and its elements get printed at runtime anyway).
|
|
stderr = run_command(code % "gc.DEBUG_SAVEALL")
|
|
self.assertNotIn(b"uncollectable objects at shutdown", stderr)
|
|
|
|
def test_gc_main_module_at_shutdown(self):
|
|
# Create a reference cycle through the __main__ module and check
|
|
# it gets collected at interpreter shutdown.
|
|
code = """if 1:
|
|
import weakref
|
|
class C:
|
|
def __del__(self):
|
|
print('__del__ called')
|
|
l = [C()]
|
|
l.append(l)
|
|
"""
|
|
rc, out, err = assert_python_ok('-c', code)
|
|
self.assertEqual(out.strip(), b'__del__ called')
|
|
|
|
def test_gc_ordinary_module_at_shutdown(self):
|
|
# Same as above, but with a non-__main__ module.
|
|
with temp_dir() as script_dir:
|
|
module = """if 1:
|
|
import weakref
|
|
class C:
|
|
def __del__(self):
|
|
print('__del__ called')
|
|
l = [C()]
|
|
l.append(l)
|
|
"""
|
|
code = """if 1:
|
|
import sys
|
|
sys.path.insert(0, %r)
|
|
import gctest
|
|
""" % (script_dir,)
|
|
make_script(script_dir, 'gctest', module)
|
|
rc, out, err = assert_python_ok('-c', code)
|
|
self.assertEqual(out.strip(), b'__del__ called')
|
|
|
|
def test_get_stats(self):
|
|
stats = gc.get_stats()
|
|
self.assertEqual(len(stats), 3)
|
|
for st in stats:
|
|
self.assertIsInstance(st, dict)
|
|
self.assertEqual(set(st),
|
|
{"collected", "collections", "uncollectable"})
|
|
self.assertGreaterEqual(st["collected"], 0)
|
|
self.assertGreaterEqual(st["collections"], 0)
|
|
self.assertGreaterEqual(st["uncollectable"], 0)
|
|
# Check that collection counts are incremented correctly
|
|
if gc.isenabled():
|
|
self.addCleanup(gc.enable)
|
|
gc.disable()
|
|
old = gc.get_stats()
|
|
gc.collect(0)
|
|
new = gc.get_stats()
|
|
self.assertEqual(new[0]["collections"], old[0]["collections"] + 1)
|
|
self.assertEqual(new[1]["collections"], old[1]["collections"])
|
|
self.assertEqual(new[2]["collections"], old[2]["collections"])
|
|
gc.collect(2)
|
|
new = gc.get_stats()
|
|
self.assertEqual(new[0]["collections"], old[0]["collections"] + 1)
|
|
self.assertEqual(new[1]["collections"], old[1]["collections"])
|
|
self.assertEqual(new[2]["collections"], old[2]["collections"] + 1)
|
|
|
|
|
|
class GCCallbackTests(unittest.TestCase):
|
|
def setUp(self):
|
|
# Save gc state and disable it.
|
|
self.enabled = gc.isenabled()
|
|
gc.disable()
|
|
self.debug = gc.get_debug()
|
|
gc.set_debug(0)
|
|
gc.callbacks.append(self.cb1)
|
|
gc.callbacks.append(self.cb2)
|
|
self.othergarbage = []
|
|
|
|
def tearDown(self):
|
|
# Restore gc state
|
|
del self.visit
|
|
gc.callbacks.remove(self.cb1)
|
|
gc.callbacks.remove(self.cb2)
|
|
gc.set_debug(self.debug)
|
|
if self.enabled:
|
|
gc.enable()
|
|
# destroy any uncollectables
|
|
gc.collect()
|
|
for obj in gc.garbage:
|
|
if isinstance(obj, Uncollectable):
|
|
obj.partner = None
|
|
del gc.garbage[:]
|
|
del self.othergarbage
|
|
gc.collect()
|
|
|
|
def preclean(self):
|
|
# Remove all fluff from the system. Invoke this function
|
|
# manually rather than through self.setUp() for maximum
|
|
# safety.
|
|
self.visit = []
|
|
gc.collect()
|
|
garbage, gc.garbage[:] = gc.garbage[:], []
|
|
self.othergarbage.append(garbage)
|
|
self.visit = []
|
|
|
|
def cb1(self, phase, info):
|
|
self.visit.append((1, phase, dict(info)))
|
|
|
|
def cb2(self, phase, info):
|
|
self.visit.append((2, phase, dict(info)))
|
|
if phase == "stop" and hasattr(self, "cleanup"):
|
|
# Clean Uncollectable from garbage
|
|
uc = [e for e in gc.garbage if isinstance(e, Uncollectable)]
|
|
gc.garbage[:] = [e for e in gc.garbage
|
|
if not isinstance(e, Uncollectable)]
|
|
for e in uc:
|
|
e.partner = None
|
|
|
|
def test_collect(self):
|
|
self.preclean()
|
|
gc.collect()
|
|
# Algorithmically verify the contents of self.visit
|
|
# because it is long and tortuous.
|
|
|
|
# Count the number of visits to each callback
|
|
n = [v[0] for v in self.visit]
|
|
n1 = [i for i in n if i == 1]
|
|
n2 = [i for i in n if i == 2]
|
|
self.assertEqual(n1, [1]*2)
|
|
self.assertEqual(n2, [2]*2)
|
|
|
|
# Count that we got the right number of start and stop callbacks.
|
|
n = [v[1] for v in self.visit]
|
|
n1 = [i for i in n if i == "start"]
|
|
n2 = [i for i in n if i == "stop"]
|
|
self.assertEqual(n1, ["start"]*2)
|
|
self.assertEqual(n2, ["stop"]*2)
|
|
|
|
# Check that we got the right info dict for all callbacks
|
|
for v in self.visit:
|
|
info = v[2]
|
|
self.assertTrue("generation" in info)
|
|
self.assertTrue("collected" in info)
|
|
self.assertTrue("uncollectable" in info)
|
|
|
|
def test_collect_generation(self):
|
|
self.preclean()
|
|
gc.collect(2)
|
|
for v in self.visit:
|
|
info = v[2]
|
|
self.assertEqual(info["generation"], 2)
|
|
|
|
@cpython_only
|
|
def test_collect_garbage(self):
|
|
self.preclean()
|
|
# Each of these cause four objects to be garbage: Two
|
|
# Uncolectables and their instance dicts.
|
|
Uncollectable()
|
|
Uncollectable()
|
|
C1055820(666)
|
|
gc.collect()
|
|
for v in self.visit:
|
|
if v[1] != "stop":
|
|
continue
|
|
info = v[2]
|
|
self.assertEqual(info["collected"], 2)
|
|
self.assertEqual(info["uncollectable"], 8)
|
|
|
|
# We should now have the Uncollectables in gc.garbage
|
|
self.assertEqual(len(gc.garbage), 4)
|
|
for e in gc.garbage:
|
|
self.assertIsInstance(e, Uncollectable)
|
|
|
|
# Now, let our callback handle the Uncollectable instances
|
|
self.cleanup=True
|
|
self.visit = []
|
|
gc.garbage[:] = []
|
|
gc.collect()
|
|
for v in self.visit:
|
|
if v[1] != "stop":
|
|
continue
|
|
info = v[2]
|
|
self.assertEqual(info["collected"], 0)
|
|
self.assertEqual(info["uncollectable"], 4)
|
|
|
|
# Uncollectables should be gone
|
|
self.assertEqual(len(gc.garbage), 0)
|
|
|
|
|
|
class GCTogglingTests(unittest.TestCase):
|
|
def setUp(self):
|
|
gc.enable()
|
|
|
|
def tearDown(self):
|
|
gc.disable()
|
|
|
|
def test_bug1055820c(self):
|
|
# Corresponds to temp2c.py in the bug report. This is pretty
|
|
# elaborate.
|
|
|
|
c0 = C1055820(0)
|
|
# Move c0 into generation 2.
|
|
gc.collect()
|
|
|
|
c1 = C1055820(1)
|
|
c1.keep_c0_alive = c0
|
|
del c0.loop # now only c1 keeps c0 alive
|
|
|
|
c2 = C1055820(2)
|
|
c2wr = weakref.ref(c2) # no callback!
|
|
|
|
ouch = []
|
|
def callback(ignored):
|
|
ouch[:] = [c2wr()]
|
|
|
|
# The callback gets associated with a wr on an object in generation 2.
|
|
c0wr = weakref.ref(c0, callback)
|
|
|
|
c0 = c1 = c2 = None
|
|
|
|
# What we've set up: c0, c1, and c2 are all trash now. c0 is in
|
|
# generation 2. The only thing keeping it alive is that c1 points to
|
|
# it. c1 and c2 are in generation 0, and are in self-loops. There's a
|
|
# global weakref to c2 (c2wr), but that weakref has no callback.
|
|
# There's also a global weakref to c0 (c0wr), and that does have a
|
|
# callback, and that callback references c2 via c2wr().
|
|
#
|
|
# c0 has a wr with callback, which references c2wr
|
|
# ^
|
|
# |
|
|
# | Generation 2 above dots
|
|
#. . . . . . . .|. . . . . . . . . . . . . . . . . . . . . . . .
|
|
# | Generation 0 below dots
|
|
# |
|
|
# |
|
|
# ^->c1 ^->c2 has a wr but no callback
|
|
# | | | |
|
|
# <--v <--v
|
|
#
|
|
# So this is the nightmare: when generation 0 gets collected, we see
|
|
# that c2 has a callback-free weakref, and c1 doesn't even have a
|
|
# weakref. Collecting generation 0 doesn't see c0 at all, and c0 is
|
|
# the only object that has a weakref with a callback. gc clears c1
|
|
# and c2. Clearing c1 has the side effect of dropping the refcount on
|
|
# c0 to 0, so c0 goes away (despite that it's in an older generation)
|
|
# and c0's wr callback triggers. That in turn materializes a reference
|
|
# to c2 via c2wr(), but c2 gets cleared anyway by gc.
|
|
|
|
# We want to let gc happen "naturally", to preserve the distinction
|
|
# between generations.
|
|
junk = []
|
|
i = 0
|
|
detector = GC_Detector()
|
|
while not detector.gc_happened:
|
|
i += 1
|
|
if i > 10000:
|
|
self.fail("gc didn't happen after 10000 iterations")
|
|
self.assertEqual(len(ouch), 0)
|
|
junk.append([]) # this will eventually trigger gc
|
|
|
|
self.assertEqual(len(ouch), 1) # else the callback wasn't invoked
|
|
for x in ouch:
|
|
# If the callback resurrected c2, the instance would be damaged,
|
|
# with an empty __dict__.
|
|
self.assertEqual(x, None)
|
|
|
|
def test_bug1055820d(self):
|
|
# Corresponds to temp2d.py in the bug report. This is very much like
|
|
# test_bug1055820c, but uses a __del__ method instead of a weakref
|
|
# callback to sneak in a resurrection of cyclic trash.
|
|
|
|
ouch = []
|
|
class D(C1055820):
|
|
def __del__(self):
|
|
ouch[:] = [c2wr()]
|
|
|
|
d0 = D(0)
|
|
# Move all the above into generation 2.
|
|
gc.collect()
|
|
|
|
c1 = C1055820(1)
|
|
c1.keep_d0_alive = d0
|
|
del d0.loop # now only c1 keeps d0 alive
|
|
|
|
c2 = C1055820(2)
|
|
c2wr = weakref.ref(c2) # no callback!
|
|
|
|
d0 = c1 = c2 = None
|
|
|
|
# What we've set up: d0, c1, and c2 are all trash now. d0 is in
|
|
# generation 2. The only thing keeping it alive is that c1 points to
|
|
# it. c1 and c2 are in generation 0, and are in self-loops. There's
|
|
# a global weakref to c2 (c2wr), but that weakref has no callback.
|
|
# There are no other weakrefs.
|
|
#
|
|
# d0 has a __del__ method that references c2wr
|
|
# ^
|
|
# |
|
|
# | Generation 2 above dots
|
|
#. . . . . . . .|. . . . . . . . . . . . . . . . . . . . . . . .
|
|
# | Generation 0 below dots
|
|
# |
|
|
# |
|
|
# ^->c1 ^->c2 has a wr but no callback
|
|
# | | | |
|
|
# <--v <--v
|
|
#
|
|
# So this is the nightmare: when generation 0 gets collected, we see
|
|
# that c2 has a callback-free weakref, and c1 doesn't even have a
|
|
# weakref. Collecting generation 0 doesn't see d0 at all. gc clears
|
|
# c1 and c2. Clearing c1 has the side effect of dropping the refcount
|
|
# on d0 to 0, so d0 goes away (despite that it's in an older
|
|
# generation) and d0's __del__ triggers. That in turn materializes
|
|
# a reference to c2 via c2wr(), but c2 gets cleared anyway by gc.
|
|
|
|
# We want to let gc happen "naturally", to preserve the distinction
|
|
# between generations.
|
|
detector = GC_Detector()
|
|
junk = []
|
|
i = 0
|
|
while not detector.gc_happened:
|
|
i += 1
|
|
if i > 10000:
|
|
self.fail("gc didn't happen after 10000 iterations")
|
|
self.assertEqual(len(ouch), 0)
|
|
junk.append([]) # this will eventually trigger gc
|
|
|
|
self.assertEqual(len(ouch), 1) # else __del__ wasn't invoked
|
|
for x in ouch:
|
|
# If __del__ resurrected c2, the instance would be damaged, with an
|
|
# empty __dict__.
|
|
self.assertEqual(x, None)
|
|
|
|
def test_main():
|
|
enabled = gc.isenabled()
|
|
gc.disable()
|
|
assert not gc.isenabled()
|
|
debug = gc.get_debug()
|
|
gc.set_debug(debug & ~gc.DEBUG_LEAK) # this test is supposed to leak
|
|
|
|
try:
|
|
gc.collect() # Delete 2nd generation garbage
|
|
run_unittest(GCTests, GCTogglingTests, GCCallbackTests)
|
|
finally:
|
|
gc.set_debug(debug)
|
|
# test gc.enable() even if GC is disabled by default
|
|
if verbose:
|
|
print("restoring automatic collection")
|
|
# make sure to always test gc.enable()
|
|
gc.enable()
|
|
assert gc.isenabled()
|
|
if not enabled:
|
|
gc.disable()
|
|
|
|
if __name__ == "__main__":
|
|
test_main()
|