Issue #7105: weak dict iterators are fragile because of unpredictable GC runs
Backport the fix from pyton 3.x for this issue.
diff --git a/Lib/test/test_weakset.py b/Lib/test/test_weakset.py
index fb9e8d7..6b34a8d 100644
--- a/Lib/test/test_weakset.py
+++ b/Lib/test/test_weakset.py
@@ -11,6 +11,7 @@
import collections
import gc
import contextlib
+from UserString import UserString as ustr
class Foo:
@@ -448,6 +449,54 @@
self.assertGreaterEqual(n2, 0)
self.assertLessEqual(n2, n1)
+ def test_weak_destroy_while_iterating(self):
+ # Issue #7105: iterators shouldn't crash when a key is implicitly removed
+ # Create new items to be sure no-one else holds a reference
+ items = [ustr(c) for c in ('a', 'b', 'c')]
+ s = WeakSet(items)
+ it = iter(s)
+ next(it) # Trigger internal iteration
+ # Destroy an item
+ del items[-1]
+ gc.collect() # just in case
+ # We have removed either the first consumed items, or another one
+ self.assertIn(len(list(it)), [len(items), len(items) - 1])
+ del it
+ # The removal has been committed
+ self.assertEqual(len(s), len(items))
+
+ def test_weak_destroy_and_mutate_while_iterating(self):
+ # Issue #7105: iterators shouldn't crash when a key is implicitly removed
+ items = [ustr(c) for c in string.ascii_letters]
+ s = WeakSet(items)
+ @contextlib.contextmanager
+ def testcontext():
+ try:
+ it = iter(s)
+ next(it)
+ # Schedule an item for removal and recreate it
+ u = ustr(str(items.pop()))
+ gc.collect() # just in case
+ yield u
+ finally:
+ it = None # should commit all removals
+
+ with testcontext() as u:
+ self.assertFalse(u in s)
+ with testcontext() as u:
+ self.assertRaises(KeyError, s.remove, u)
+ self.assertFalse(u in s)
+ with testcontext() as u:
+ s.add(u)
+ self.assertTrue(u in s)
+ t = s.copy()
+ with testcontext() as u:
+ s.update(t)
+ self.assertEqual(len(s), len(t))
+ with testcontext() as u:
+ s.clear()
+ self.assertEqual(len(s), 0)
+
def test_main(verbose=None):
test_support.run_unittest(TestWeakSet)