[issue42745] [subinterpreters] Make the type lookup cache per-interpreter

[STINNER Victor]

New submission from STINNER Victor <vstinner at python.org>:

Currently, the type lookup cache is shared by all interpreter which causes multiple issues:

* The version tag is currently protected by the GIL, but it would require a new lock if the GIL is made per interpreter (bpo-40512)

* Clearing the cache in an interpreter clears the cache in all interpreters

* The cache has a fixed size of 4096 entries. The cache misses increase with the number of interpreters, since each interpreter has its own types.

I propose to make the type lookup cache per interpreter.

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components: Interpreter Core, Subinterpreters
messages: 383777
nosy: vstinner
priority: normal
severity: normal
status: open
title: [subinterpreters] Make the type lookup cache per-interpreter
versions: Python 3.10

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue42745>
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