Shuffling actors

[Sergey Kuksenko]

Hi,

Right now actors are submitted to executor in the source code order. 
That may reduce chance to catch some interesting race.
I'd like to suggest to make shuffle actors before each submit.

E.g.

@Outcome(expect = Expect.ACCEPTABLE, desc ="acceptable")
@State public class CFTest1 {

     final CompletableFuture<Void>start =new CompletableFuture<Void>();
     CompletableFuture<String>f;

     // r1 - completion thread // r2 - chain construction thread // r3 - 
action thread @Actor public void actor1(LLL_Result r) {
         start.complete(null);
         r.r1 = Thread.currentThread().getName();
     }

     @Actor public void actor2(LLL_Result r) {
         f =start.thenApply(v -> Thread.currentThread().getName());// add action r.r2 = Thread.currentThread().getName();

     }

     @Arbiter public void arbiter(LLL_Result r) {
         r.r3 =f.join();
     }

}

That example always shows results:

      [OK] org.openjdk.jcstress.samples.CFTest1
     (JVM args: [])
                                            Observed state   Occurrences   Expectation  Interpretation
   jcstress-worker-1, jcstress-worker-2, jcstress-worker-2     6,960,000    ACCEPTABLE  acceptable
   jcstress-worker-2, jcstress-worker-1, jcstress-worker-1    35,544,928    ACCEPTABLE  acceptable

(action is always performed in the chain construction thread)

When actor1 & actor2 are interchanged in the source code, I've got:

    [OK] org.openjdk.jcstress.samples.CFTest1
     (JVM args: [])
                                            Observed state   Occurrences   Expectation  Interpretation
   jcstress-worker-1, jcstress-worker-2, jcstress-worker-1     4,888,350    ACCEPTABLE  acceptable
   jcstress-worker-2, jcstress-worker-1, jcstress-worker-1    35,843,340    ACCEPTABLE  acceptable
   jcstress-worker-2, jcstress-worker-1, jcstress-worker-2        32,768    ACCEPTABLE  acceptable

another case was caught - action was performed in the completion thread.

I understand that on another HW/OS/JDK/etc I could get opposite results, therefore shuffling actors is important.

-- 
Best regards,
Sergey Kuksenko