[Python-checkins] r54706 - python/trunk/Lib/test/test_gc.py
collin.winter
python-checkins at python.org
Fri Apr 6 22:00:10 CEST 2007
Author: collin.winter
Date: Fri Apr 6 22:00:05 2007
New Revision: 54706
Modified:
python/trunk/Lib/test/test_gc.py
Log:
Convert test_gc to use unittest.
Modified: python/trunk/Lib/test/test_gc.py
==============================================================================
--- python/trunk/Lib/test/test_gc.py (original)
+++ python/trunk/Lib/test/test_gc.py Fri Apr 6 22:00:05 2007
@@ -1,391 +1,12 @@
-from test.test_support import verify, verbose, TestFailed, vereq
+import unittest
+from test.test_support import verbose, run_unittest
import sys
import gc
import weakref
-def expect(actual, expected, name):
- if actual != expected:
- raise TestFailed, "test_%s: actual %r, expected %r" % (
- name, actual, expected)
-
-def expect_nonzero(actual, name):
- if actual == 0:
- raise TestFailed, "test_%s: unexpected zero" % name
-
-def run_test(name, thunk):
- if verbose:
- print "testing %s..." % name,
- thunk()
- if verbose:
- print "ok"
-
-def test_list():
- l = []
- l.append(l)
- gc.collect()
- del l
- expect(gc.collect(), 1, "list")
-
-def test_dict():
- d = {}
- d[1] = d
- gc.collect()
- del d
- expect(gc.collect(), 1, "dict")
-
-def test_tuple():
- # since tuples are immutable we close the loop with a list
- l = []
- t = (l,)
- l.append(t)
- gc.collect()
- del t
- del l
- expect(gc.collect(), 2, "tuple")
-
-def test_class():
- class A:
- pass
- A.a = A
- gc.collect()
- del A
- expect_nonzero(gc.collect(), "class")
-
-def test_newstyleclass():
- class A(object):
- pass
- gc.collect()
- del A
- expect_nonzero(gc.collect(), "staticclass")
-
-def test_instance():
- class A:
- pass
- a = A()
- a.a = a
- gc.collect()
- del a
- expect_nonzero(gc.collect(), "instance")
-
-def test_newinstance():
- class A(object):
- pass
- a = A()
- a.a = a
- gc.collect()
- del a
- expect_nonzero(gc.collect(), "newinstance")
- class B(list):
- pass
- class C(B, A):
- pass
- a = C()
- a.a = a
- gc.collect()
- del a
- expect_nonzero(gc.collect(), "newinstance(2)")
- del B, C
- expect_nonzero(gc.collect(), "newinstance(3)")
- A.a = A()
- del A
- expect_nonzero(gc.collect(), "newinstance(4)")
- expect(gc.collect(), 0, "newinstance(5)")
-
-def test_method():
- # 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
- expect_nonzero(gc.collect(), "method")
-
-def test_finalizer():
- # A() is uncollectable if it is part of a cycle, make sure it shows up
- # in gc.garbage.
- class A:
- def __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
- expect_nonzero(gc.collect(), "finalizer")
- for obj in gc.garbage:
- if id(obj) == id_a:
- del obj.a
- break
- else:
- raise TestFailed, "didn't find obj in garbage (finalizer)"
- gc.garbage.remove(obj)
-
-def test_finalizer_newclass():
- # A() is uncollectable if it is part of a cycle, make sure it shows up
- # in gc.garbage.
- class A(object):
- def __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
- expect_nonzero(gc.collect(), "finalizer")
- for obj in gc.garbage:
- if id(obj) == id_a:
- del obj.a
- break
- else:
- raise TestFailed, "didn't find obj in garbage (finalizer)"
- gc.garbage.remove(obj)
-
-def test_function():
- # Tricky: f -> d -> f, code should call d.clear() after the exec to
- # break the cycle.
- d = {}
- exec("def f(): pass\n") in d
- gc.collect()
- del d
- expect(gc.collect(), 2, "function")
-
-def test_frame():
- def f():
- frame = sys._getframe()
- gc.collect()
- f()
- expect(gc.collect(), 1, "frame")
-
-
-def test_saveall():
- # 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()
- vereq(gc.garbage, []) # if this fails, someone else created immortal trash
-
- 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)
-
- vereq(len(gc.garbage), 1)
- obj = gc.garbage.pop()
- vereq(id(obj), id_L)
-
-def test_del():
- # __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():
- # __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)
-
-def test_get_count():
- gc.collect()
- expect(gc.get_count(), (0, 0, 0), "get_count()")
- a = dict()
- expect(gc.get_count(), (1, 0, 0), "get_count()")
-
-def test_collect_generations():
- gc.collect()
- a = dict()
- gc.collect(0)
- expect(gc.get_count(), (0, 1, 0), "collect(0)")
- gc.collect(1)
- expect(gc.get_count(), (0, 0, 1), "collect(1)")
- gc.collect(2)
- expect(gc.get_count(), (0, 0, 0), "collect(1)")
-
-class Ouch:
- n = 0
- def __del__(self):
- Ouch.n = Ouch.n + 1
- if Ouch.n % 17 == 0:
- gc.collect()
-
-def test_trashcan():
- # "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()
-
-class Boom:
- def __getattr__(self, someattribute):
- del self.attr
- raise AttributeError
-
-def test_boom():
- 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.
- expect(gc.collect(), 4, "boom")
- expect(len(gc.garbage), garbagelen, "boom")
-
-class Boom2:
- def __init__(self):
- self.x = 0
-
- def __getattr__(self, someattribute):
- self.x += 1
- if self.x > 1:
- del self.attr
- raise AttributeError
-
-def test_boom2():
- 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.
- expect(gc.collect(), 4, "boom2")
- expect(len(gc.garbage), garbagelen, "boom2")
-
-# 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
-
-def test_boom_new():
- a = Boom_New()
- b = Boom_New()
- a.attr = b
- b.attr = a
-
- gc.collect()
- garbagelen = len(gc.garbage)
- del a, b
- expect(gc.collect(), 4, "boom_new")
- expect(len(gc.garbage), garbagelen, "boom_new")
-
-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
-
-def test_boom2_new():
- a = Boom2_New()
- b = Boom2_New()
- a.attr = b
- b.attr = a
-
- gc.collect()
- garbagelen = len(gc.garbage)
- del a, b
- expect(gc.collect(), 4, "boom2_new")
- expect(len(gc.garbage), garbagelen, "boom2_new")
-
-def test_get_referents():
- alist = [1, 3, 5]
- got = gc.get_referents(alist)
- got.sort()
- expect(got, alist, "get_referents")
-
- atuple = tuple(alist)
- got = gc.get_referents(atuple)
- got.sort()
- expect(got, alist, "get_referents")
-
- adict = {1: 3, 5: 7}
- expected = [1, 3, 5, 7]
- got = gc.get_referents(adict)
- got.sort()
- expect(got, expected, "get_referents")
-
- got = gc.get_referents([1, 2], {3: 4}, (0, 0, 0))
- got.sort()
- expect(got, [0, 0] + range(5), "get_referents")
-
- expect(gc.get_referents(1, 'a', 4j), [], "get_referents")
-
+### Support code
+###############################################################################
+
# Bug 1055820 has several tests of longstanding bugs involving weakrefs and
# cyclic gc.
@@ -410,217 +31,556 @@
# gc collects it.
self.wr = weakref.ref(C1055820(666), it_happened)
-def test_bug1055820b():
- # 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()
- expect(len(ouch), 0, "bug1055820b")
- # 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()
- expect(len(ouch), 2, "bug1055820b") # 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__.
- expect(x, None, "bug1055820b")
-
-def test_bug1055820c():
- # 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:
- raise TestFailed("gc didn't happen after 10000 iterations")
- expect(len(ouch), 0, "bug1055820c")
- junk.append([]) # this will eventually trigger gc
-
- expect(len(ouch), 1, "bug1055820c") # else the callback wasn't invoked
- for x in ouch:
- # If the callback resurrected c2, the instance would be damaged,
- # with an empty __dict__.
- expect(x, None, "bug1055820c")
-
-def test_bug1055820d():
- # 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()]
+### 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)
+
+ 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)
+
+ def test_finalizer(self):
+ # A() is uncollectable if it is part of a cycle, make sure it shows up
+ # in gc.garbage.
+ class A:
+ def __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)
+
+ def test_finalizer_newclass(self):
+ # A() is uncollectable if it is part of a cycle, make sure it shows up
+ # in gc.garbage.
+ class A(object):
+ def __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") in d
+ gc.collect()
+ del d
+ self.assertEqual(gc.collect(), 2)
+
+ 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)
- 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:
- raise TestFailed("gc didn't happen after 10000 iterations")
- expect(len(ouch), 0, "bug1055820d")
- junk.append([]) # this will eventually trigger gc
-
- expect(len(ouch), 1, "bug1055820d") # else __del__ wasn't invoked
- for x in ouch:
- # If __del__ resurrected c2, the instance would be damaged, with an
- # empty __dict__.
- expect(x, None, "bug1055820d")
-
-
-def test_all():
- gc.collect() # Delete 2nd generation garbage
- run_test("lists", test_list)
- run_test("dicts", test_dict)
- run_test("tuples", test_tuple)
- run_test("classes", test_class)
- run_test("new style classes", test_newstyleclass)
- run_test("instances", test_instance)
- run_test("new instances", test_newinstance)
- run_test("methods", test_method)
- run_test("functions", test_function)
- run_test("frames", test_frame)
- run_test("finalizers", test_finalizer)
- run_test("finalizers (new class)", test_finalizer_newclass)
- run_test("__del__", test_del)
- run_test("__del__ (new class)", test_del_newclass)
- run_test("get_count()", test_get_count)
- run_test("collect(n)", test_collect_generations)
- run_test("saveall", test_saveall)
- run_test("trashcan", test_trashcan)
- run_test("boom", test_boom)
- run_test("boom2", test_boom2)
- run_test("boom_new", test_boom_new)
- run_test("boom2_new", test_boom2_new)
- run_test("get_referents", test_get_referents)
- run_test("bug1055820b", test_bug1055820b)
+ 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.enable()
- try:
- run_test("bug1055820c", test_bug1055820c)
- finally:
gc.disable()
+ gc.set_threshold(*thresholds)
- gc.enable()
- try:
- run_test("bug1055820d", test_bug1055820d)
- finally:
+ 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)
+
+ def test_get_count(self):
+ gc.collect()
+ self.assertEqual(gc.get_count(), (0, 0, 0))
+ a = dict()
+ self.assertEqual(gc.get_count(), (1, 0, 0))
+
+ def test_collect_generations(self):
+ gc.collect()
+ a = dict()
+ gc.collect(0)
+ self.assertEqual(gc.get_count(), (0, 1, 0))
+ gc.collect(1)
+ self.assertEqual(gc.get_count(), (0, 0, 1))
+ gc.collect(2)
+ self.assertEqual(gc.get_count(), (0, 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_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] + range(5))
+
+ self.assertEqual(gc.get_referents(1, 'a', 4j), [])
+
+ 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)
+
+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()]
-def test():
- if verbose:
- print "disabling automatic collection"
+ # 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()
- verify(not gc.isenabled())
+ assert not gc.isenabled()
debug = gc.get_debug()
gc.set_debug(debug & ~gc.DEBUG_LEAK) # this test is supposed to leak
try:
- test_all()
+ gc.collect() # Delete 2nd generation garbage
+ run_unittest(GCTests, GCTogglingTests)
finally:
gc.set_debug(debug)
# test gc.enable() even if GC is disabled by default
@@ -628,9 +588,9 @@
print "restoring automatic collection"
# make sure to always test gc.enable()
gc.enable()
- verify(gc.isenabled())
+ assert gc.isenabled()
if not enabled:
gc.disable()
-
-
-test()
+
+if __name__ == "__main__":
+ test_main()
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