RFR: 8316142: Enable parallelism in vmTestbase/nsk/monitoring/stress/lowmem tests

[David Holmes]

On Tue, 12 Sep 2023 19:20:16 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Similar to [JDK-8315437](https://bugs.openjdk.org/browse/JDK-8315437), current vmTestbase/nsk/monitoring/stress/lowmem tests contains 36 tests, each running exclusively. This drags the tier4 test times up. There seem to be no reason to run these tests exclusively, though: they complete in reasonable time, are moderately-threaded, and consume the usual amount of memory.
> 
> We should consider enabling parallelism for them and get improved test performance. Currently it is blocked by TEST.properties with exclusiveAccess.dirs directives in them.
> 
> Current run on 18-core machine:
>  6385.39s user 8568.61s system 1308% cpu 19:02.97 total
> 
> Fully parallel:
>  3885.67s user 295.13s system 2772% cpu 2:30.77 total 
> 
> Additional testing:
>  - [x] 100x Linux x86_64 fastdebug, `vmTestbase/nsk/monitoring/stress/lowmem`

No objections here. We will just have to be vigilant about the tests modified here.

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PR Comment: https://git.openjdk.org/jdk/pull/15689#issuecomment-1722915665