diff --git a/numpy/lib/tests/test_io.py b/numpy/lib/tests/test_io.py index 06c57d49cc2b..09a70a388947 100644 --- a/numpy/lib/tests/test_io.py +++ b/numpy/lib/tests/test_io.py @@ -23,7 +23,7 @@ from numpy.testing import ( assert_warns, assert_, SkipTest, assert_raises_regex, assert_raises, assert_allclose, assert_array_equal, temppath, tempdir, IS_PYPY, - HAS_REFCOUNT, suppress_warnings, + HAS_REFCOUNT, suppress_warnings, assert_no_gc_cycles, ) @@ -2369,14 +2369,5 @@ def test_load_refcount(): np.savez(f, [1, 2, 3]) f.seek(0) - assert_(gc.isenabled()) - gc.disable() - try: - gc.collect() + with assert_no_gc_cycles(): np.load(f) - # gc.collect returns the number of unreachable objects in cycles that - # were found -- we are checking that no cycles were created by np.load - n_objects_in_cycles = gc.collect() - finally: - gc.enable() - assert_equal(n_objects_in_cycles, 0) diff --git a/numpy/testing/_private/utils.py b/numpy/testing/_private/utils.py index 507ecb1e2740..b0c0b0c48f23 100644 --- a/numpy/testing/_private/utils.py +++ b/numpy/testing/_private/utils.py @@ -7,6 +7,7 @@ import os import sys import re +import gc import operator import warnings from functools import partial, wraps @@ -14,6 +15,7 @@ import contextlib from tempfile import mkdtemp, mkstemp from unittest.case import SkipTest +import pprint from numpy.core import( float32, empty, arange, array_repr, ndarray, isnat, array) @@ -35,7 +37,7 @@ 'assert_allclose', 'IgnoreException', 'clear_and_catch_warnings', 'SkipTest', 'KnownFailureException', 'temppath', 'tempdir', 'IS_PYPY', 'HAS_REFCOUNT', 'suppress_warnings', 'assert_array_compare', - '_assert_valid_refcount', '_gen_alignment_data', + '_assert_valid_refcount', '_gen_alignment_data', 'assert_no_gc_cycles', ] @@ -2272,3 +2274,89 @@ def new_func(*args, **kwargs): return func(*args, **kwargs) return new_func + + +@contextlib.contextmanager +def _assert_no_gc_cycles_context(name=None): + __tracebackhide__ = True # Hide traceback for py.test + + # not meaningful to test if there is no refcounting + if not HAS_REFCOUNT: + return + + assert_(gc.isenabled()) + gc.disable() + gc_debug = gc.get_debug() + try: + for i in range(100): + if gc.collect() == 0: + break + else: + raise RuntimeError( + "Unable to fully collect garbage - perhaps a __del__ method is " + "creating more reference cycles?") + + gc.set_debug(gc.DEBUG_SAVEALL) + yield + # gc.collect returns the number of unreachable objects in cycles that + # were found -- we are checking that no cycles were created in the context + n_objects_in_cycles = gc.collect() + objects_in_cycles = gc.garbage[:] + finally: + del gc.garbage[:] + gc.set_debug(gc_debug) + gc.enable() + + if n_objects_in_cycles: + name_str = " when calling %s" % name if name is not None else "" + raise AssertionError( + "Reference cycles were found{}: {} objects were collected, " + "of which {} are shown below:{}" + .format( + name_str, + n_objects_in_cycles, + len(objects_in_cycles), + ''.join( + "\n {} object with id={}:\n {}".format( + type(o).__name__, + id(o), + pprint.pformat(o).replace('\n', '\n ') + ) for o in objects_in_cycles + ) + ) + ) + + +def assert_no_gc_cycles(*args, **kwargs): + """ + Fail if the given callable produces any reference cycles. + + If called with all arguments omitted, may be used as a context manager: + + with assert_no_gc_cycles(): + do_something() + + .. versionadded:: 1.15.0 + + Parameters + ---------- + func : callable + The callable to test. + \\*args : Arguments + Arguments passed to `func`. + \\*\\*kwargs : Kwargs + Keyword arguments passed to `func`. + + Returns + ------- + Nothing. The result is deliberately discarded to ensure that all cycles + are found. + + """ + if not args: + return _assert_no_gc_cycles_context() + + func = args[0] + args = args[1:] + with _assert_no_gc_cycles_context(name=func.__name__): + func(*args, **kwargs) diff --git a/numpy/testing/tests/test_utils.py b/numpy/testing/tests/test_utils.py index 35f81d8a7a66..0592e62f8e1b 100644 --- a/numpy/testing/tests/test_utils.py +++ b/numpy/testing/tests/test_utils.py @@ -6,6 +6,7 @@ import itertools import textwrap import pytest +import weakref import numpy as np from numpy.testing import ( @@ -14,7 +15,7 @@ assert_raises, assert_warns, assert_no_warnings, assert_allclose, assert_approx_equal, assert_array_almost_equal_nulp, assert_array_max_ulp, clear_and_catch_warnings, suppress_warnings, assert_string_equal, assert_, - tempdir, temppath, + tempdir, temppath, assert_no_gc_cycles, HAS_REFCOUNT ) @@ -1360,3 +1361,76 @@ def test_clear_and_catch_warnings_inherit(): warnings.simplefilter('ignore') warnings.warn('Some warning') assert_equal(my_mod.__warningregistry__, {}) + + +@pytest.mark.skipif(not HAS_REFCOUNT, reason="Python lacks refcounts") +class TestAssertNoGcCycles(object): + """ Test assert_no_gc_cycles """ + def test_passes(self): + def no_cycle(): + b = [] + b.append([]) + return b + + with assert_no_gc_cycles(): + no_cycle() + + assert_no_gc_cycles(no_cycle) + + + def test_asserts(self): + def make_cycle(): + a = [] + a.append(a) + a.append(a) + return a + + with assert_raises(AssertionError): + with assert_no_gc_cycles(): + make_cycle() + + with assert_raises(AssertionError): + assert_no_gc_cycles(make_cycle) + + + def test_fails(self): + """ + Test that in cases where the garbage cannot be collected, we raise an + error, instead of hanging forever trying to clear it. + """ + + class ReferenceCycleInDel(object): + """ + An object that not only contains a reference cycle, but creates new + cycles whenever it's garbage-collected and its __del__ runs + """ + make_cycle = True + + def __init__(self): + self.cycle = self + + def __del__(self): + # break the current cycle so that `self` can be freed + self.cycle = None + + if ReferenceCycleInDel.make_cycle: + # but create a new one so that the garbage collector has more + # work to do. + ReferenceCycleInDel() + + try: + w = weakref.ref(ReferenceCycleInDel()) + try: + with assert_raises(RuntimeError): + # this will be unable to get a baseline empty garbage + assert_no_gc_cycles(lambda: None) + except AssertionError: + # the above test is only necessary if the GC actually tried to free + # our object anyway, which python 2.7 does not. + if w() is not None: + pytest.skip("GC does not call __del__ on cyclic objects") + raise + + finally: + # make sure that we stop creating reference cycles + ReferenceCycleInDel.make_cycle = False diff --git a/numpy/testing/utils.py b/numpy/testing/utils.py index 78cf405cfac4..184adcc74c68 100644 --- a/numpy/testing/utils.py +++ b/numpy/testing/utils.py @@ -25,5 +25,5 @@ 'assert_allclose', 'IgnoreException', 'clear_and_catch_warnings', 'SkipTest', 'KnownFailureException', 'temppath', 'tempdir', 'IS_PYPY', 'HAS_REFCOUNT', 'suppress_warnings', 'assert_array_compare', - '_assert_valid_refcount', '_gen_alignment_data', + '_assert_valid_refcount', '_gen_alignment_data', 'assert_no_gc_cycles' ]