[3.12] gh-106931: Intern Statically Allocated Strings Globally (gh-107272)#107358
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…gh-107272) We tried this before with a dict and for all interned strings. That ran into problems due to interpreter isolation. However, exclusively using a per-interpreter cache caused some inconsistency that can eliminate the benefit of interning. Here we circle back to using a global cache, but only for statically allocated strings. We also use a more-basic _Py_hashtable_t for that global cache instead of a dict. Ideally we would only have the global cache, but the optional isolation of each interpreter's allocator means that a non-static string object must not outlive its interpreter. Thus we would have to store a copy of each such interned string in the global cache, tied to the main interpreter. (cherry picked from commit b72947a) Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
This was referenced Jul 27, 2023
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ericsnowcurrently commented Jul 27, 2023
As noted elsewhere, I'm going to mull over whether or not this is worth it in 3.12. CC @Yhg1s |
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ericsnowcurrently commented Jul 28, 2023
Having slept on it, I don't see this change as important enough to be worth backporting, particularly given the release manager's reservations. |
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ericsnowcurrently commented Oct 4, 2023
This may be needed to fix gh-110279. |
This was referenced Oct 4, 2023
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We tried this before with a dict and for all interned strings. That ran into problems due to interpreter isolation. However, exclusively using a per-interpreter cache caused some inconsistency that can eliminate the benefit of interning. Here we circle back to using a global cache, but only for statically allocated strings. We also use a more-basic _Py_hashtable_t for that global cache instead of a dict.
Ideally we would only have the global cache, but the optional isolation of each interpreter's allocator means that a non-static string object must not outlive its interpreter. Thus we would have to store a copy of each such interned string in the global cache, tied to the main interpreter.
(cherry picked from commit b72947a)
Co-authored-by: Eric Snow ericsnowcurrently@gmail.com