RFR: 8247980: Exclusive execution of java/util/stream tests slows down tier1

[Paul Sandoz]

On Thu, 19 Aug 2021 15:15:31 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> See the bug report for more details. I would appreciate if people with their corporate testing systems would run this through their systems to avoid surprises. (ping @RealCLanger, @iignatev).

Struggling to recall all the details. I think in part the tests were made exclusive to avoid the greedy parallel tests potentially competing with the execution of other greedy parallel stream tests and other independent tests.

The issue may be petrubed when using machines with a large number of cores, as cost of greedly using all hardware threads is counter productive to the data sizes. It may be useful if we could limit the parallelism of stream tests on machines with large cores. I don't recall if we currently do that or have explored that.

There may be no ideal configuration that fits machines with small and large cores. If there is a prioritization i would lean towards optimization by default for the automated test infra with options to modify that default for others running the tests.

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PR: https://git.openjdk.java.net/jdk/pull/5189