RFR(S) : 8243431 : use reproducible random in :vmTestbase_vm_metaspace

[David Holmes]

Hi Igor,

tl;dr LGTM! :)

On 1/05/2020 3:13 am, Igor Ignatyev wrote:
> http://cr.openjdk.java.net/~iignatyev/8243431/webrev.00
>> 27 lines changed: 23 ins; 0 del; 4 mod;
> 
> Hi all,
> 
> could you please review this small patch?
> from JBS:
>> this subtask is to use j.t.l.Utils.getRandomInstance() as a random number generator, where applicable, in : vmTestbase_vm_metaspace test group and marking the tests which make use of "randomness" with a proper k/w.

Okay so three kinds of changes here:

- trivial addition of randomness keyword
- use of getRandomInstance() where applicable
- broader changes to introduce reproducability

The last one threw me a bit as it wasn't expected from your summary. So 
looking at:

vmTestbase/metaspace/stressDictionary/StressDictionary.java

This test already uses a Random instance with a well-defined seed for 
reproducability. The problem is that is used by multiple threads so 
their own uses are non-deterministic due to scheduling. Hence you have 
now created a random instance per worker thread, seed from the shared 
Random instance. Okay - makes sense.

Thanks,
David

> testing: : vmTestbase_vm_metaspace test group
> JBS: https://bugs.openjdk.java.net/browse/JDK-8243431
> webrevs:
> - code changes: http://cr.openjdk.java.net/~iignatyev//8243431/webrev.00.code
>> 7 lines changed: 5 ins; 0 del; 2 mod;
> - adding k/w: http://cr.openjdk.java.net/~iignatyev//8243431/webrev.00.kw
>> 18 lines changed: 18 ins; 0 del; 0 mod;
> - full: http://cr.openjdk.java.net/~iignatyev//8243431/webrev.00
>> 27 lines changed: 23 ins; 0 del; 4 mod;
> 
> Thanks,
> -- Igor
>