RFR: 8319650: Improve heap dump performance with class metadata caching [v3]

[Aleksey Shipilev]

On Thu, 9 Nov 2023 15:20:59 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Maybe? Need to brush up my knowledge on non-power-of-two hash tables. This thing just copies the hash we have in other places :) But since we are looking at it, I see no grand point in overriding the hash code here, and we can just use the default one. When/if default one improves, this one should improve as well.
>
> The reason I asked is that we use this primitive_hash for a lot of hashtables of InstanceKlass and Symbol so if your experiments saw too many collisions, it would be good to change for everything.

No, I just copy-pasted it without thinking all too much about the existence of the default hash code. I don't see much, if any, difference with default hashcode in my quick tests. So I left the default.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16545#discussion_r1388183290