RFR: 8255756: Disabling logging does unnecessary work [v2]

[Ioi Lam]

On Thu, 5 Nov 2020 10:59:21 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> When disabling UL outputs - for example when shutting down the JVM - we are doing some unnecessary work:
>> 
>> - we always disable all outputs in bulk, but the routine searches up outputs one by one in the LogTagSet output lists - instead we could just drop all nodes in these lists in one quick pass.
>> - when finalizing for a JVM shutdown, it's unnecessary to update decorators
>> 
>> While not technically startup this gets rid of some noise on JVM exit (~45k instructions) that show up when using full JVM executions as a proxy for startup testing (or when running many shortlived JVMs back-to-back).
>
> Claes Redestad 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 10 additional commits since the last revision:
> 
>  - clear should mimic remove_output and wait_until_no_readers before deleting nodes
>  - Merge branch 'master' into disable_logging
>  - Improve wording
>  - Remove extra lines
>  - Clean up and fix clear
>  - Shortcut clearing of all outputs from tagsets
>  - Shortcut clearing of all outputs from tagsets
>  - Fix loop
>  - Merge branch 'master' into disable_logging
>  - Disabling logging outputs on exit does unnecessary work

Lgtm

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Marked as reviewed by iklam (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1005