--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/python-2.5.2/win32/Lib/test/test_gc.py Fri Apr 03 17:19:34 2009 +0100
@@ -0,0 +1,636 @@
+from test.test_support import verify, verbose, TestFailed, vereq
+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")
+
+# 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)
+
+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()]
+
+ 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)
+
+ gc.enable()
+ try:
+ run_test("bug1055820c", test_bug1055820c)
+ finally:
+ gc.disable()
+
+ gc.enable()
+ try:
+ run_test("bug1055820d", test_bug1055820d)
+ finally:
+ gc.disable()
+
+def test():
+ if verbose:
+ print "disabling automatic collection"
+ enabled = gc.isenabled()
+ gc.disable()
+ verify(not gc.isenabled())
+ debug = gc.get_debug()
+ gc.set_debug(debug & ~gc.DEBUG_LEAK) # this test is supposed to leak
+
+ try:
+ test_all()
+ 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()
+ verify(gc.isenabled())
+ if not enabled:
+ gc.disable()
+
+
+test()