Strange behaviour on half-occupied heap

[Simon Ogorodnik]

> On 29 Aug 2018, at 17:30, Aleksey Shipilev <shade at redhat.com> wrote:
> 
> I have to make sure it works reliably everywhere, and then push it. Meanwhile, you can try set
> -XX:ShenandoahMaxCSetFactor=60, and watch the "Trigger" lines. Or, give it more headroom in heap.
> 
> -Aleksey
> 

Even with -XX:ShenandoahMaxCSetFactor=60 same situation reproduces. 

I recorded visualiser:
https://drive.google.com/file/d/1uhJiGE3kCCDZNbOds6G853u7AmSlPbs0/view?usp=sharing


Also, I noted that intense collections continues even after Full GC without reason to, and stops a bit later
Looks like another heuristics problem
Trigger: Average GC time (367.04 ms) is above the time for allocation rate (54.06 MB/s) to deplete free headroom (0M)
Trigger: Average GC time (356.68 ms) is above the time for allocation rate (43.52 MB/s) to deplete free headroom (0M)
Trigger: Average GC time (339.38 ms) is above the time for allocation rate (54.77 MB/s) to deplete free headroom (0M)
Trigger: Average GC time (320.57 ms) is above the time for allocation rate (47.51 MB/s) to deplete free headroom (0M)
Trigger: Average GC time (320.43 ms) is above the time for allocation rate (38.27 MB/s) to deplete free headroom (0M)

Full logs: 
https://drive.google.com/file/d/1vfrj-Lk7_GEU3XlKQG7iSereyBqGfQ5s/view?usp=sharing