JezK
Edit File: test_gc.py
import gc import weakref import greenlet from . import TestCase from .leakcheck import fails_leakcheck # These only work with greenlet gc support # which is no longer optional. assert greenlet.GREENLET_USE_GC class GCTests(TestCase): def test_dead_circular_ref(self): o = weakref.ref(greenlet.greenlet(greenlet.getcurrent).switch()) gc.collect() if o() is not None: import sys print("O IS NOT NONE.", sys.getrefcount(o())) self.assertIsNone(o()) self.assertFalse(gc.garbage, gc.garbage) def test_circular_greenlet(self): class circular_greenlet(greenlet.greenlet): pass o = circular_greenlet() o.self = o o = weakref.ref(o) gc.collect() self.assertIsNone(o()) self.assertFalse(gc.garbage, gc.garbage) def test_inactive_ref(self): class inactive_greenlet(greenlet.greenlet): def __init__(self): greenlet.greenlet.__init__(self, run=self.run) def run(self): pass o = inactive_greenlet() o = weakref.ref(o) gc.collect() self.assertIsNone(o()) self.assertFalse(gc.garbage, gc.garbage) @fails_leakcheck def test_finalizer_crash(self): # This test is designed to crash when active greenlets # are made garbage collectable, until the underlying # problem is resolved. How does it work: # - order of object creation is important # - array is created first, so it is moved to unreachable first # - we create a cycle between a greenlet and this array # - we create an object that participates in gc, is only # referenced by a greenlet, and would corrupt gc lists # on destruction, the easiest is to use an object with # a finalizer # - because array is the first object in unreachable it is # cleared first, which causes all references to greenlet # to disappear and causes greenlet to be destroyed, but since # it is still live it causes a switch during gc, which causes # an object with finalizer to be destroyed, which causes stack # corruption and then a crash class object_with_finalizer(object): def __del__(self): pass array = [] parent = greenlet.getcurrent() def greenlet_body(): greenlet.getcurrent().object = object_with_finalizer() try: parent.switch() except greenlet.GreenletExit: print("Got greenlet exit!") finally: del greenlet.getcurrent().object g = greenlet.greenlet(greenlet_body) g.array = array array.append(g) g.switch() del array del g greenlet.getcurrent() gc.collect()