RFR: Grand heuristics and tests rehash

[Zhengyu Gu]

Looks good.

-Zhengyu

On 09/06/2018 06:50 AM, Aleksey Shipilev wrote:
> http://cr.openjdk.java.net/~shade/shenandoah/heuristics-tests/webrev.01/
> 
> This includes several interconnected changesets:
> 
>   *) Passive heuristics now goes to Degenerated GC first, and then maybe to Full GC. This allows more
> precise barrier overhead measurements, because we would be execute the exact same cycle, but in STW
> mode.
> 
>   *) Remove partial heuristics from testing. They are not used by anyone, and testing with them takes
> significant time. Instead, we have their own special test that verify partial heuristics are not
> terribly broken.
> 
>   *) Reshuffling the test configurations. The motivation for it is simple. We first test "passive"
> with either Degen or Full GC, to capture egregious mistakes in the GC code itself. Then we test
> "aggressive", along with all exceptional corner cases that the cycle might run into. Then we test
> default concurrent modes which can expose some new bugs, and only then special configs.
> 
>   *) TestHeapDump is much faster when we tune down its heap, because heap traversal resets the bitmap
> for the heap, and that takes time for larger heap.
> 
> This cuts down tier3 testing time from 35 minutes to 25 minutes on my desktop.
> 
> Testing: tier3_gc_shenandoah
> 
> Thanks,
> -Aleksey
>