I'm seeing test failures in transience when running the tests for Zope-2_7-branch (python 2.3.3) with garbage collection threshold0 set to 1. Seems to break in slightly different places from run to run. Here is one example: % python test.py -vv --dir lib/python/Products/Transience/tests -g 1 "" "testPathological" gc threshold: (1, 10, 10) Running unit tests at level 1 Running unit tests from /Zope/lib/python/Products/Transience/tests testPathologicalLeftBranching (Products.Transience.tests.testTransientObjectContainer.TestTransientObj ectContainer) ... ERROR testPathologicalRightBranching (Products.Transience.tests.testTransientObjectContainer.TestTransientObj ectContainer) ... ERROR ====================================================================== ERROR: testPathologicalLeftBranching (Products.Transience.tests.testTransientObjectContainer.TestTransientObj ectContainer) ---------------------------------------------------------------------- Traceback (most recent call last): File "/Zope/lib/python/Products/Transience/tests/ testTransientObjectContainer.py", line 193, in testPathologicalLeftBranching map(self.t.__delitem__, revr) File "/Zope/lib/python/Products/Transience/Transience.py", line 470, in __delitem__ del bucket[k] KeyError: 946 ====================================================================== ERROR: testPathologicalRightBranching (Products.Transience.tests.testTransientObjectContainer.TestTransientObj ectContainer) ---------------------------------------------------------------------- Traceback (most recent call last): File "/Zope/lib/python/Products/Transience/tests/ testTransientObjectContainer.py", line 183, in testPathologicalRightBranching map(self.t.__delitem__, r) File "/Zope/lib/python/Products/Transience/Transience.py", line 470, in __delitem__ del bucket[k] KeyError: 69 ---------------------------------------------------------------------- Ran 2 tests in 4.659s FAILED (errors=2)