RFR: 8364103: Convert existing sprintf-chains to stringStream [v2]

[Ioi Lam]

On Thu, 4 Sep 2025 13:12:35 GMT, Paul Hübner <phubner at openjdk.org> wrote:

>> Hi all,
>> 
>> This PR refactors `javaClasses`' `print_stack_element_to_stream` to use a `stringStream` instead of manually maintaining a buffer with `os::snprintf` chains.
>> 
>> The JBS issue outlines to do this for all occurrences of `snprintf`-like chains. The majority of the calls to `os::snprintf`, `os::snprintf_checked`, `os::vsnprintf`, etc. occur just once. `LogTagSet::vwrite` is the only place to my knowledge where there remains a `vsnprintf` chain using manual buffer arithmetic. After consulting @jdksjolen, we decided that due to the
>> a) low-level nature of the code, and 
>> b) widespread usage of logging in the VM, 
>> this should probably warrant a larger discussion and/or separate issue. Personally, I feel like the performance & correctness risks of introducing a high-level abstraction here outweighs the benefits. 
>> 
>> I've run tests with JDK tiers 1-3 on macOS (AArch64, x64), Linux (AArch64, x64), and Windows (x64); all green.
>
> Paul Hübner has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:
> 
>  - Incorporate reviewer feedback.
>  - Merge branch 'master' into JDK-8364103
>  - Refactor stack trace printing to use stringStream.

LGTM.

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Marked as reviewed by iklam (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26894#pullrequestreview-3185929582