RFR: 8321971: Improve the user name detection logic in perfMemory get_user_name_slow [v3]

[Jaikiran Pai]

On Wed, 20 Dec 2023 07:29:07 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Can I please get a review of this change which proposes to improve the code in `get_user_name_slow` function, which is used to identify the target JVM owner's user name? This addresses https://bugs.openjdk.org/browse/JDK-8321971.
>> 
>> As noted in that JBS issue, in its current form, the nested loop ends up iterating over the directory contents of `hsperfdata_xxx` directory and then for each iteration it checks if the name of the entry matches the pid. This iteration shouldn't be needed and instead one could look for a file named `<pid>` within that directory.
>> 
>> No new test has been added, given the nature of this change. Existing tier1, tier2, tier3 and svc_tools tests pass with this change on Linux, Windows and macosx.
>
> Jaikiran Pai has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
> 
>  - remove redundant if block
>  - merge latest from master branch
>  - David's review comments - reduce if blocks and release the array outside if block
>  - David's review comment - punctuation
>  - 8321971: Improve the user name detection logic in perfMemory get_user_name_slow

Just a note - I have incorporated the review comments, except from Johan which I'm still investigating and will update this PR soon.

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PR Comment: https://git.openjdk.org/jdk/pull/17104#issuecomment-1864379594