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from test_support import verify, verbose, TestFailed
import sys
import gc
def expect(actual, expected, name):
if actual != expected:
raise TestFailed, "test_%s: actual %d, expected %d" % (
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_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.
debug = gc.get_debug()
gc.set_debug(debug | gc.DEBUG_SAVEALL)
l = []
l.append(l)
id_l = id(l)
del l
gc.collect()
try:
for obj in gc.garbage:
if id(obj) == id_l:
del obj[:]
break
else:
raise TestFailed, "didn't find obj in garbage (saveall)"
gc.garbage.remove(obj)
finally:
gc.set_debug(debug)
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()
apply(gc.set_threshold, thresholds)
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()
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("__del__", test_del)
run_test("saveall", test_saveall)
run_test("trashcan", test_trashcan)
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()
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