GH-132380: Add optimization for non-interned type lookup. #132652
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colesbury
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Apr 21, 2025
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| /* Keep a strong reference to mro because type->tp_mro can be replaced | ||
| during dict lookup, e.g. when comparing to non-string keys. */ | ||
| mro = _PyType_GetMRO(type); |
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Won't this lead to reference count contention?
I don't think we need to skip the cache in this case. The names are exact unicode objects, they're just not interned. If the string isn't interned can we use a different loop in the lookup code that uses something like PyUnicode_Compare?
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Closing since this is an approach we don't want to take. |
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Add an optimized implementation of type lookup for names that are non-interned strings. This is only enabled for free-threaded builds since that kind of lookup can cause contention for the global type lock.
I benchmarked this with LibCST running on the numpy source code. Summary of results:
_PyType_LookupRef#132380The backport to 3.13 of this is non-trivial and so I made a separate PR for it (GH-132651). It is basically the same logic though. This approach to avoid the contention might be preferred to GH-132381 since I think it should be more obviously safe.
Benchmark results from pyperformance