RFR: 8347734: Turning off PerfData logging doesn't work

[David Holmes]

On Thu, 13 Mar 2025 15:07:07 GMT, Casper Norrbin <cnorrbin at openjdk.org> wrote:

> Hi everyone,
> 
> When PerfData is disabled, the corresponding perfdata variables remain uninitialized. However, under certain conditions, logging may attempt to access these variables, leading to a crash. The existing code turns off the relevant tags using `LogConfiguration::configure_stdout`, but this doesn't modify other outputs. For example, the test `runtime/logging/RedefineClasses.java` crashes with `-XX:-UsePerfData` because it uses an output that isn't stdout.
> 
> To fix this, I've added a new method `LogConfiguration::disable_tags`. Unlike `configure_stdout`, this function iterates over all outputs and disables the specified tags on each. This way, we correctly disable tags across all outputs and longer try and access the uninitialized perfdata variables.

This looks good to me. Thanks for fixing it Casper!

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Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24036#pullrequestreview-2689171336