diff -r 000000000000 -r ae805ac0140d python-2.5.2/win32/Lib/test/test_gc.py --- /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()