RFR: 8364103: Convert existing sprintf-chains to stringStream

Paul Hübner duke at openjdk.org
Fri Aug 22 08:58:34 UTC 2025


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.

-------------

Commit messages:
 - Refactor stack trace printing to use stringStream.

Changes: https://git.openjdk.org/jdk/pull/26894/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26894&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364103
  Stats: 20 lines in 1 file changed: 1 ins; 6 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/26894.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26894/head:pull/26894

PR: https://git.openjdk.org/jdk/pull/26894


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