| import unittest | |
| from test.support import (verbose, refcount_test, run_unittest, | |
| strip_python_stderr, cpython_only, start_threads, | |
| temp_dir, requires_type_collecting, TESTFN, unlink) | |
| from test.support.script_helper import assert_python_ok, make_script | |
| import sys | |
| import time | |
| import gc | |
| import weakref | |
| import threading | |
| try: | |
| from _testcapi import with_tp_del | |
| except ImportError: | |
| def with_tp_del(cls): | |
| class C(object): | |
| def __new__(cls, *args, **kwargs): | |
| raise TypeError('requires _testcapi.with_tp_del') | |
| return C | |
| ### Support code | |
| ############################################################################### | |
| # Bug 1055820 has several tests of longstanding bugs involving weakrefs and | |
| # cyclic gc. | |
| # An instance of C1055820 has a self-loop, so becomes cyclic trash when | |
| # unreachable. | |
| class C1055820(object): | |
| def __init__(self, i): | |
| self.i = i | |
| self.loop = self | |
| class GC_Detector(object): | |
| # Create an instance I. Then gc hasn't happened again so long as | |
| # I.gc_happened is false. | |
| def __init__(self): | |
| self.gc_happened = False | |
| def it_happened(ignored): | |
| self.gc_happened = True | |
| # Create a piece of cyclic trash that triggers it_happened when | |
| # gc collects it. | |
| self.wr = weakref.ref(C1055820(666), it_happened) | |
| @with_tp_del | |
| class Uncollectable(object): | |
| """Create a reference cycle with multiple __del__ methods. | |
| An object in a reference cycle will never have zero references, | |
| and so must be garbage collected. If one or more objects in the | |
| cycle have __del__ methods, the gc refuses to guess an order, | |
| and leaves the cycle uncollected.""" | |
| def __init__(self, partner=None): | |
| if partner is None: | |
| self.partner = Uncollectable(partner=self) | |
| else: | |
| self.partner = partner | |
| def __tp_del__(self): | |
| pass | |
| ### Tests | |
| ############################################################################### | |
| class GCTests(unittest.TestCase): | |
| def test_list(self): | |
| l = [] | |
| l.append(l) | |
| gc.collect() | |
| del l | |
| self.assertEqual(gc.collect(), 1) | |
| def test_dict(self): | |
| d = {} | |
| d[1] = d | |
| gc.collect() | |
| del d | |
| self.assertEqual(gc.collect(), 1) | |
| def test_tuple(self): | |
| # since tuples are immutable we close the loop with a list | |
| l = [] | |
| t = (l,) | |
| l.append(t) | |
| gc.collect() | |
| del t | |
| del l | |
| self.assertEqual(gc.collect(), 2) | |
| def test_class(self): | |
| class A: | |
| pass | |
| A.a = A | |
| gc.collect() | |
| del A | |
| self.assertNotEqual(gc.collect(), 0) | |
| def test_newstyleclass(self): | |
| class A(object): | |
| pass | |
| gc.collect() | |
| del A | |
| self.assertNotEqual(gc.collect(), 0) | |
| def test_instance(self): | |
| class A: | |
| pass | |
| a = A() | |
| a.a = a | |
| gc.collect() | |
| del a | |
| self.assertNotEqual(gc.collect(), 0) | |
| @requires_type_collecting | |
| def test_newinstance(self): | |
| class A(object): | |
| pass | |
| a = A() | |
| a.a = a | |
| gc.collect() | |
| del a | |
| self.assertNotEqual(gc.collect(), 0) | |
| class B(list): | |
| pass | |
| class C(B, A): | |
| pass | |
| a = C() | |
| a.a = a | |
| gc.collect() | |
| del a | |
| self.assertNotEqual(gc.collect(), 0) | |
| del B, C | |
| self.assertNotEqual(gc.collect(), 0) | |
| A.a = A() | |
| del A | |
| self.assertNotEqual(gc.collect(), 0) | |
| self.assertEqual(gc.collect(), 0) | |
| def test_method(self): | |
| # Tricky: self.__init__ is a bound method, it references the instance. | |
| class A: | |
| def __init__(self): | |
| self.init = self.__init__ | |
| a = A() | |
| gc.collect() | |
| del a | |
| self.assertNotEqual(gc.collect(), 0) | |
| @cpython_only | |
| def test_legacy_finalizer(self): | |
| # A() is uncollectable if it is part of a cycle, make sure it shows up | |
| # in gc.garbage. | |
| @with_tp_del | |
| class A: | |
| def __tp_del__(self): pass | |
| class B: | |
| pass | |
| a = A() | |
| a.a = a | |
| id_a = id(a) | |
| b = B() | |
| b.b = b | |
| gc.collect() | |
| del a | |
| del b | |
| self.assertNotEqual(gc.collect(), 0) | |
| for obj in gc.garbage: | |
| if id(obj) == id_a: | |
| del obj.a | |
| break | |
| else: | |
| self.fail("didn't find obj in garbage (finalizer)") | |
| gc.garbage.remove(obj) | |
| @cpython_only | |
| def test_legacy_finalizer_newclass(self): | |
| # A() is uncollectable if it is part of a cycle, make sure it shows up | |
| # in gc.garbage. | |
| @with_tp_del | |
| class A(object): | |
| def __tp_del__(self): pass | |
| class B(object): | |
| pass | |
| a = A() | |
| a.a = a | |
| id_a = id(a) | |
| b = B() | |
| b.b = b | |
| gc.collect() | |
| del a | |
| del b | |
| self.assertNotEqual(gc.collect(), 0) | |
| for obj in gc.garbage: | |
| if id(obj) == id_a: | |
| del obj.a | |
| break | |
| else: | |
| self.fail("didn't find obj in garbage (finalizer)") | |
| gc.garbage.remove(obj) | |
| def test_function(self): | |
| # Tricky: f -> d -> f, code should call d.clear() after the exec to | |
| # break the cycle. | |
| d = {} | |
| exec("def f(): pass\n", d) | |
| gc.collect() | |
| del d | |
| self.assertEqual(gc.collect(), 2) | |
| @refcount_test | |
| def test_frame(self): | |
| def f(): | |
| frame = sys._getframe() | |
| gc.collect() | |
| f() | |
| self.assertEqual(gc.collect(), 1) | |
| def test_saveall(self): | |
| # Verify that cyclic garbage like lists show up in gc.garbage if the | |
| # SAVEALL option is enabled. | |
| # First make sure we don't save away other stuff that just happens to | |
| # be waiting for collection. | |
| gc.collect() | |
| # if this fails, someone else created immortal trash | |
| self.assertEqual(gc.garbage, []) | |
| L = [] | |
| L.append(L) | |
| id_L = id(L) | |
| debug = gc.get_debug() | |
| gc.set_debug(debug | gc.DEBUG_SAVEALL) | |
| del L | |
| gc.collect() | |
| gc.set_debug(debug) | |
| self.assertEqual(len(gc.garbage), 1) | |
| obj = gc.garbage.pop() | |
| self.assertEqual(id(obj), id_L) | |
| def test_del(self): | |
| # __del__ methods can trigger collection, make this to happen | |
| thresholds = gc.get_threshold() | |
| gc.enable() | |
| gc.set_threshold(1) | |
| class A: | |
| def __del__(self): | |
| dir(self) | |
| a = A() | |
| del a | |
| gc.disable() | |
| gc.set_threshold(*thresholds) | |
| def test_del_newclass(self): | |
| # __del__ methods can trigger collection, make this to happen | |
| thresholds = gc.get_threshold() | |
| gc.enable() | |
| gc.set_threshold(1) | |
| class A(object): | |
| def __del__(self): | |
| dir(self) | |
| a = A() | |
| del a | |
| gc.disable() | |
| gc.set_threshold(*thresholds) | |
| # The following two tests are fragile: | |
| # They precisely count the number of allocations, | |
| # which is highly implementation-dependent. | |
| # For example, disposed tuples are not freed, but reused. | |
| # To minimize variations, though, we first store the get_count() results | |
| # and check them at the end. | |
| @refcount_test | |
| def test_get_count(self): | |
| gc.collect() | |
| a, b, c = gc.get_count() | |
| x = [] | |
| d, e, f = gc.get_count() | |
| self.assertEqual((b, c), (0, 0)) | |
| self.assertEqual((e, f), (0, 0)) | |
| # This is less fragile than asserting that a equals 0. | |
| self.assertLess(a, 5) | |
| # Between the two calls to get_count(), at least one object was | |
| # created (the list). | |
| self.assertGreater(d, a) | |
| @refcount_test | |
| def test_collect_generations(self): | |
| gc.collect() | |
| # This object will "trickle" into generation N + 1 after | |
| # each call to collect(N) | |
| x = [] | |
| gc.collect(0) | |
| # x is now in gen 1 | |
| a, b, c = gc.get_count() | |
| gc.collect(1) | |
| # x is now in gen 2 | |
| d, e, f = gc.get_count() | |
| gc.collect(2) | |
| # x is now in gen 3 | |
| g, h, i = gc.get_count() | |
| # We don't check a, d, g since their exact values depends on | |
| # internal implementation details of the interpreter. | |
| self.assertEqual((b, c), (1, 0)) | |
| self.assertEqual((e, f), (0, 1)) | |
| self.assertEqual((h, i), (0, 0)) | |
| def test_trashcan(self): | |
| class Ouch: | |
| n = 0 | |
| def __del__(self): | |
| Ouch.n = Ouch.n + 1 | |
| if Ouch.n % 17 == 0: | |
| gc.collect() | |
| # "trashcan" is a hack to prevent stack overflow when deallocating | |
| # very deeply nested tuples etc. It works in part by abusing the | |
| # type pointer and refcount fields, and that can yield horrible | |
| # problems when gc tries to traverse the structures. | |
| # If this test fails (as it does in 2.0, 2.1 and 2.2), it will | |
| # most likely die via segfault. | |
| # Note: In 2.3 the possibility for compiling without cyclic gc was | |
| # removed, and that in turn allows the trashcan mechanism to work | |
| # via much simpler means (e.g., it never abuses the type pointer or | |
| # refcount fields anymore). Since it's much less likely to cause a | |
| # problem now, the various constants in this expensive (we force a lot | |
| # of full collections) test are cut back from the 2.2 version. | |
| gc.enable() | |
| N = 150 | |
| for count in range(2): | |
| t = [] | |
| for i in range(N): | |
| t = [t, Ouch()] | |
| u = [] | |
| for i in range(N): | |
| u = [u, Ouch()] | |
| v = {} | |
| for i in range(N): | |
| v = {1: v, 2: Ouch()} | |
| gc.disable() | |
| def test_trashcan_threads(self): | |
| # Issue #13992: trashcan mechanism should be thread-safe | |
| NESTING = 60 | |
| N_THREADS = 2 | |
| def sleeper_gen(): | |
| """A generator that releases the GIL when closed or dealloc'ed.""" | |
| try: | |
| yield | |
| finally: | |
| time.sleep(0.000001) | |
| class C(list): | |
| # Appending to a list is atomic, which avoids the use of a lock. | |
| inits = [] | |
| dels = [] | |
| def __init__(self, alist): | |
| self[:] = alist | |
| C.inits.append(None) | |
| def __del__(self): | |
| # This __del__ is called by subtype_dealloc(). | |
| C.dels.append(None) | |
| # `g` will release the GIL when garbage-collected. This | |
| # helps assert subtype_dealloc's behaviour when threads | |
| # switch in the middle of it. | |
| g = sleeper_gen() | |
| next(g) | |
| # Now that __del__ is finished, subtype_dealloc will proceed | |
| # to call list_dealloc, which also uses the trashcan mechanism. | |
| def make_nested(): | |
| """Create a sufficiently nested container object so that the | |
| trashcan mechanism is invoked when deallocating it.""" | |
| x = C([]) | |
| for i in range(NESTING): | |
| x = [C([x])] | |
| del x | |
| def run_thread(): | |
| """Exercise make_nested() in a loop.""" | |
| while not exit: | |
| make_nested() | |
| old_switchinterval = sys.getswitchinterval() | |
| sys.setswitchinterval(1e-5) | |
| try: | |
| exit = [] | |
| threads = [] | |
| for i in range(N_THREADS): | |
| t = threading.Thread(target=run_thread) | |
| threads.append(t) | |
| with start_threads(threads, lambda: exit.append(1)): | |
| time.sleep(1.0) | |
| finally: | |
| sys.setswitchinterval(old_switchinterval) | |
| gc.collect() | |
| self.assertEqual(len(C.inits), len(C.dels)) | |
| def test_boom(self): | |
| class Boom: | |
| def __getattr__(self, someattribute): | |
| del self.attr | |
| raise AttributeError | |
| a = Boom() | |
| b = Boom() | |
| a.attr = b | |
| b.attr = a | |
| gc.collect() | |
| garbagelen = len(gc.garbage) | |
| del a, b | |
| # a<->b are in a trash cycle now. Collection will invoke | |
| # Boom.__getattr__ (to see whether a and b have __del__ methods), and | |
| # __getattr__ deletes the internal "attr" attributes as a side effect. | |
| # That causes the trash cycle to get reclaimed via refcounts falling to | |
| # 0, thus mutating the trash graph as a side effect of merely asking | |
| # whether __del__ exists. This used to (before 2.3b1) crash Python. | |
| # Now __getattr__ isn't called. | |
| self.assertEqual(gc.collect(), 4) | |
| self.assertEqual(len(gc.garbage), garbagelen) | |
| def test_boom2(self): | |
| class Boom2: | |
| def __init__(self): | |
| self.x = 0 | |
| def __getattr__(self, someattribute): | |
| self.x += 1 | |
| if self.x > 1: | |
| del self.attr | |
| raise AttributeError | |
| a = Boom2() | |
| b = Boom2() | |
| a.attr = b | |
| b.attr = a | |
| gc.collect() | |
| garbagelen = len(gc.garbage) | |
| del a, b | |
| # Much like test_boom(), except that __getattr__ doesn't break the | |
| # cycle until the second time gc checks for __del__. As of 2.3b1, | |
| # there isn't a second time, so this simply cleans up the trash cycle. | |
| # We expect a, b, a.__dict__ and b.__dict__ (4 objects) to get | |
| # reclaimed this way. | |
| self.assertEqual(gc.collect(), 4) | |
| self.assertEqual(len(gc.garbage), garbagelen) | |
| def test_boom_new(self): | |
| # boom__new and boom2_new are exactly like boom and boom2, except use | |
| # new-style classes. | |
| class Boom_New(object): | |
| def __getattr__(self, someattribute): | |
| del self.attr | |
| raise AttributeError | |
| a = Boom_New() | |
| b = Boom_New() | |
| a.attr = b | |
| b.attr = a | |
| gc.collect() | |
| garbagelen = len(gc.garbage) | |
| del a, b | |
| self.assertEqual(gc.collect(), 4) | |
| self.assertEqual(len(gc.garbage), garbagelen) | |
| def test_boom2_new(self): | |
| class Boom2_New(object): | |
| def __init__(self): | |
| self.x = 0 | |
| def __getattr__(self, someattribute): | |
| self.x += 1 | |
| if self.x > 1: | |
| del self.attr | |
| raise AttributeError | |
| a = Boom2_New() | |
| b = Boom2_New() | |
| a.attr = b | |
| b.attr = a | |
| gc.collect() | |
| garbagelen = len(gc.garbage) | |
| del a, b | |
| self.assertEqual(gc.collect(), 4) | |
| self.assertEqual(len(gc.garbage), garbagelen) | |
| def test_get_referents(self): | |
| alist = [1, 3, 5] | |
| got = gc.get_referents(alist) | |
| got.sort() | |
| self.assertEqual(got, alist) | |
| atuple = tuple(alist) | |
| got = gc.get_referents(atuple) | |
| got.sort() | |
| self.assertEqual(got, alist) | |
| adict = {1: 3, 5: 7} | |
| expected = [1, 3, 5, 7] | |
| got = gc.get_referents(adict) | |
| got.sort() | |
| self.assertEqual(got, expected) | |
| got = gc.get_referents([1, 2], {3: 4}, (0, 0, 0)) | |
| got.sort() | |
| self.assertEqual(got, [0, 0] + list(range(5))) | |
| self.assertEqual(gc.get_referents(1, 'a', 4j), []) | |
| def test_is_tracked(self): | |
| # Atomic built-in types are not tracked, user-defined objects and | |
| # mutable containers are. | |
| # NOTE: types with special optimizations (e.g. tuple) have tests | |
| # in their own test files instead. | |
| self.assertFalse(gc.is_tracked(None)) | |
| self.assertFalse(gc.is_tracked(1)) | |
| self.assertFalse(gc.is_tracked(1.0)) | |
| self.assertFalse(gc.is_tracked(1.0 + 5.0j)) | |
| self.assertFalse(gc.is_tracked(True)) | |
| self.assertFalse(gc.is_tracked(False)) | |
| self.assertFalse(gc.is_tracked(b"a")) | |
| self.assertFalse(gc.is_tracked("a")) | |
| self.assertFalse(gc.is_tracked(bytearray(b"a"))) | |
| self.assertFalse(gc.is_tracked(type)) | |
| self.assertFalse(gc.is_tracked(int)) | |
| self.assertFalse(gc.is_tracked(object)) | |
| self.assertFalse(gc.is_tracked(object())) | |
| class UserClass: | |
| pass | |
| class UserInt(int): | |
| pass | |
| # Base class is object; no extra fields. | |
| class UserClassSlots: | |
| __slots__ = () | |
| # Base class is fixed size larger than object; no extra fields. | |
| class UserFloatSlots(float): | |
| __slots__ = () | |
| # Base class is variable size; no extra fields. | |
| class UserIntSlots(int): | |
| __slots__ = () | |
| self.assertTrue(gc.is_tracked(gc)) | |
| self.assertTrue(gc.is_tracked(UserClass)) | |
| self.assertTrue(gc.is_tracked(UserClass())) | |
| self.assertTrue(gc.is_tracked(UserInt())) | |
| self.assertTrue(gc.is_tracked([])) | |
| self.assertTrue(gc.is_tracked(set())) | |
| self.assertFalse(gc.is_tracked(UserClassSlots())) | |
| self.assertFalse(gc.is_tracked(UserFloatSlots())) | |
| self.assertFalse(gc.is_tracked(UserIntSlots())) | |
| 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) | |
| @requires_type_collecting | |
| 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: | |
| 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') | |
| @requires_type_collecting | |
| 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: | |
| 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') | |
| @requires_type_collecting | |
| def test_global_del_SystemExit(self): | |
| code = """if 1: | |
| class ClassWithDel: | |
| def __del__(self): | |
| print('__del__ called') | |
| a = ClassWithDel() | |
| a.link = a | |
| raise SystemExit(0)""" | |
| self.addCleanup(unlink, TESTFN) | |
| with open(TESTFN, 'w') as script: | |
| script.write(code) | |
| rc, out, err = assert_python_ok(TESTFN) | |
| 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) | |
| def test_freeze(self): | |
| gc.freeze() | |
| self.assertGreater(gc.get_freeze_count(), 0) | |
| gc.unfreeze() | |
| self.assertEqual(gc.get_freeze_count(), 0) | |
| 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() |