ShenandoahStrDedupStress.java test

[Zhengyu Gu]

Hi,

I ran ShenandoahStrDedupStress test with Shenandoah jdk10 (our own 
implementation) and current Shenandoah jdk head (shared implementation) 
with -/+ ClassUnloadingWithConcurrentMark, all tests took about 24 - 27 
minutes.

ClassUnloadingWithConcurrentMark is not a factor, since the test always 
generates 10K unique strings.

What you observed is that, it takes longer than used to? or it simply 
takes too long?

BTW, I think we should probably move all stress tests to tier3, and make 
tier2 the criteria for pushing? and run tier3 for nightly test?

It, especially for fastdebug build, takes toooo long to run for me.


Thanks,

-Zhengyu