Caching the tuple hash calculation speeds up some code significantly

[mdboom]

Proposal:

Back in 2013, it was determined that caching the result of tuple_hash did not have any significant speedup.

However, a lot has changed since then, and in a recent experiment to add a tuple hash cache back in, the mdp benchmark increased by 86%.

Admittedly, there was no measurable improvement on any other benchmark, but it also seems to have no downside, including for memory usage when measured with max_rss.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

• [ ]

Linked PRs

• gh-131525: Cache the result of tuple_hash #131529
• gh-131525: Remove _HashedSeq wrapper from lru_cache #131922

[rhettinger]

This would nicely simplify and speed-up the pure python implementation of lru_cache. The _HashedSeq class would no longer be needed, and a plain tuple would suffice.