RFR: Comprehensible GC trigger logging

[Roman Kennke]

Am 21.08.2018 um 19:12 schrieb Aleksey Shipilev:
> http://cr.openjdk.java.net/~shade/shenandoah/compreh-trigger/webrev.01/
> 
> Our current logs are confusing if you want to figure out why exactly the GC had triggered. We need
> to make them more comprehensible and user-friendly. It does so by telling exactly why the control
> code decided to trigger the GC. It also does it with "gc" tag, not with "gc+ergo", because that bit
> is the most important bit that heuristics tell.
> 
> The patch also eliminates ShenandoahAllocThreshold handling from free-threshold-based heuristics,
> for simplicity. The value for that option is 0 by default, so it has no effect anyway.
> 
> Testing: tier3_gc_shenandoah
> 
> Thanks,
> -Aleksey
> 

Very good! Push it!

Thanks,
Roman