RFR: 7902989: jcstress: Add samples for high-level race conditions [v7]

[Michael Mirwaldt]

On Fri, 2 Jul 2021 15:02:56 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Frankly speaking, I think `1: v=200, 1: t1=250, 2: v=200, 2: t2=100, 2: v=t2, 1: v=t1` is too complicated.
>> 
>> Do you think `200` is important for the test case?
>> Would it be better to use `0` starting point?
>> What if only `+` was used?
>> 
>> For instance: "actor 1 uses 10", and "actor2 uses 20". It would be easier than "actor1 uses 100 and actor2 uses 50" because 1-100; 2-50 is harder than 1-10; 2-20;
>> 
>> suppose the actors only add values to the accumulator, then
>> 
>> Boring results would be:
>> `10, 30, 30: actor1: 0+10; actor2: 10+20`
>> `30, 20, 30: actor2: 0+20; actor1: 20+10`
>> 
>> interesting results would be
>> `10, 20, 10; actor1: 0+10; actor2: 0+20; arbiter observes actor1 result`
>> `10, 20, 20; actor1: 0+10; actor2: 0+20; arbiter observes actor2 result`
>
> Let's just move on. I prefer this description -- https://github.com/openjdk/jcstress/pull/88#discussion_r663076870 -- and that's it.

Accepted and committed. Thank you, @shipilev for your final proposal!

Just some last remarks for @vlsi:
This read-modify-write sequence reminded me of the popular example of a bank account where one spouse deposits some money (+50) while the other spouse withdraws money (-100). Therefore, I chose 200 as initial value, too.
I must confess that I consider your proposal as confusing to me as my proposal was confusing to you ;-)
However, I think it was good that we tried all that out: If something is confusing to you or to me, then it might be confusing for other users as well.

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PR: https://git.openjdk.java.net/jcstress/pull/88