RFR: 8316581: Improve performance of Symbol::print_value_on()

[Aleksey Shipilev]

On Wed, 20 Sep 2023 09:34:05 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   please review this (hopefully correct) optimization of `Symbol::print_value_on()`; investigation into class unloading time distribution showed that a lot of time is spent in the `UnloadingEventLog::log()` call (25+%, see CR).
> 
> The reason seems to be the use of `outputStream::print()` without any need for formatting.
> 
> This seems to decrease time spent in this logging by almost 10x.
> 
> Testing: hs_err output seems still be the same, GHA
> 
> Thanks,
>   Thomas

Seems to be similar to what `java_lang_Class::print_signature` already does: https://github.com/openjdk/jdk/blob/e1870d360e05c372e672b519d7de2a60c333675b/src/hotspot/share/classfile/javaClasses.cpp#L1296 -- might replace that one with the call to `Symbol::print_value_on` (maybe later).

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/15838#pullrequestreview-1635238150