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