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test_track_literals depends on a garbage collection #155728
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The failing test assertion were added in #140575. cc @vstinner, @efimov-mikhail.
Do you mind I will take this?
You are welcome.
Maybe
(1,)can be rewritten asx=1; (x,)to avoid storing the tuple as a constant.while ./python -m unittest test.test_tuple.TupleTest.test_track_literals passes.
I understand that this issue is more theorical since it's not possible to get a failure when running
test_tuple.You can get failure by running
./python -m test test_tuple -m test_track_literals.It means that the test asserts wrong condition. The result depends on previously executed code, it is not invariant.
Ah thanks, it's good to have a way to reproduce the issue.
There are two aspects to this problem: one with flowgraph optimizations (the CFG should produce untracked tuples where possible), and the second with marshal (since optimization results are cached in
__pycache__).I'd like to open two separate PRs — one for flowgraph + tupleobject changes, one for marshal.
Does that work?
Reacted by Mikhail Efimov
Bug report
_not_tracked_instantly()requires the tuple to be untracked without a collection. This holds for tuples created at run time, but tuple constants are created tracked and are only untracked by_PyTuple_MaybeUntrack(), which is called only from the collector.So
test_track_literalspasses only if a collection happens between importing the module and running the test. Under regrtest it does not:while
./python -m unittest test.test_tuple.TupleTest.test_track_literalspasses.Untracking tuple constants when the code object is created would let the test keep the stronger check.
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