RFR: 8292407: Improve Weak CAS VarHandle/Unsafe tests resilience under spurious failures [v2]

[Vladimir Kempik]

On Tue, 16 Aug 2022 15:48:15 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> We have a few reports that existing Weak* VarHandle tests are still flaky, for example on large AArch64 machines or small RISC-V machines.
>> 
>> The flakiness is intrinsic to the nature of Weak* operations under tests, that can spuriously fail. The last attempt to fix these was [JDK-8155739](https://bugs.openjdk.org/browse/JDK-8155739). We need to strengthen these a bit more.
>> 
>> The actual values depend on the successful testing on known-failing platforms. I ballparked bumping the attempts 5x and introducing the delay would help without exploding test time in worst cases.
>
> Aleksey Shipilev has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Update copyrights
>  - Also do Unsafe tests

new patch test results: thead rvb-ice - all good.
hifive unmatched: some tests still fail intermittently ( with timeout factor 10, to prevent them timing out):
VarHandleTestAccessShort.java
VarHandleTestMethodHandleAccess*.java

Will probably have to ignore these in test runs.

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PR: https://git.openjdk.org/jdk/pull/9889