gh-141510: Optimize hash(frozendict)#144919
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vstinner merged 2 commits intopython:mainfrom Feb 17, 2026
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hash(frozendict) no longer creates a temporary items view and a temporary frozenset object. Copy frozenset_hash() code to frozendict_hash().
corona10
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Feb 17, 2026
| Py_hash_t hash = FT_ATOMIC_LOAD_SSIZE_RELAXED(self->ma_hash); | ||
| if (hash != -1) { | ||
| return hash; | ||
| Py_hash_t shash = FT_ATOMIC_LOAD_SSIZE_RELAXED(self->ma_hash); |
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Why atomic operation is needed?
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PyFrozenDictObject.ma_hash is mutable and so it needs a lock to handle properly concurrent access.
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It's the same for the Unicode strings hash: the string is immutable, but the hash member is mutable. So unicode_hash() uses atomic operations to get and set the hash member.
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Yeah, the hash is "lazily" computed so we need to use relaxed atomics here.
corona10
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Feb 17, 2026
kumaraditya303
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Feb 17, 2026
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Merged, thanks for reviews! |
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hash(frozendict) no longer creates a temporary items view and a temporary frozenset object.
Copy frozenset_hash() code to frozendict_hash().