G1GC, Java8u40ea, Metaspace questions

[Wolfgang Pedot]

One more, something just came to me:

Class unloading happens during the concurrent marking-cycle so the mixed 
collects that would free up unused classloaders in oldGen happen after 
that, right?
That would mean the classes can only be cleaned up at the next cycle and 
stay in Metaspace until then. My test causes only Metaspace-triggered 
concurrent cycles so the garbage-collector is always behind by one cycle 
and therefor the amount of classes that can be unloaded can be different 
each time, irregardless of the percentage of wasted heap. I guess I have 
to extend my test-scenario in a way that also causes at least some 
heap-driven concurrent cycles and see what happens then.
Still does not explain why I hardly ever see HWM go down but it explains 
some of my more confusing test-results...

regards
Wolfgang