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

[Aleksey Shipilev]

On Thu, 9 Nov 2023 13:51:27 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
>> 
>>  - Limit the table size
>>  - Merge branch 'master' into JDK-8319650-heapdump-cache-meta
>>  - Fix
>
> src/hotspot/share/services/heapDumper.cpp line 825:
> 
>> 823:   static constexpr int CACHE_TOP = 256;
>> 824: 
>> 825:   static unsigned int ptr_hash(void* const& s1) {
> 
> Should we change primitive_hash to this? (not this PR)

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.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16545#discussion_r1388118205