RFR: 8270333: -XX:+VerifyStringTableAtExit should not do linear search

[David Holmes]

On Wed, 14 Jul 2021 02:34:19 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> The implementation of `-XX:+VerifyStringTableAtExit` used a linear search to check for duplicated strings in the interned string table. This would be excessively slow if there were more than a few thousand strings.
> 
> This PR uses a hashtable so we can avoid doing a linear search. The table is sized such that each bucket has 8 items on average.
> 
> Since this code is executed only for verification, I added a new `java_lang_String::hash_code_noupdate(oop)` function, so we can avoid causing side effects.

Changes seem fine, but I don't like your use of templates here.

Thanks,
David

src/hotspot/share/classfile/javaClasses.cpp line 506:

> 504: 
> 505: template<bool update>
> 506: unsigned int java_lang_String::hash_code_impl(oop java_string) {

This looks like a really weird way to pass a parameter! Why do we want a template here?

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/4772