Fwd: RFR (XXS) 8212932: [TESTBUG] Clean up TestVirtualSpaceNode test

[gerard ziemski]

Hi all,

Please review this small change where we remove 
test/hotspot/gtest/memory/test_virtualSpaceNode.cpp

For the reason as to why we decided to remove it, as opposed to cleaning 
it up (which was under consideration - I fixed some of its issues in 
JDK-8216493), I’m providing here a quote from Thomas Stuefe:

“I feel that since 8198423 its usefulness is greatly diminished, and 
there is a bit of a danger of getting it wrong, messing up global 
structures in metaspace and affecting follow up tests. Metaspace is not 
(anymore) designed to be used on this isolated level.

I really thought long and hard about this. Unfortunately, this test 
cannot be done in an isolated fashion anymore without affecting global 
metaspace - sure you encountered that yourself, hence the terrible 
(sorry :-) ChunkManagerRestorer workaround. And I do not see a better 
way to do this.

All these tests do now is to ensure that a particular notion of chunk 
geometry and allocation behavior is adhered to - stuff which may change 
anyway since it is implementation detail. I do not see any really 
worthwhile tests. And the fact that since 8198423 any allocation from a 
VirtualSpaceNode can cause allocation of padding chunks, which get added 
to the global freelist and hence change global state, makes matters 
quite complicated."

bug: https://bugs.openjdk.java.net/browse/JDK-8212932
webrev: http://cr.openjdk.java.net/~gziemski/8212932_rev1
testing: passes "make test-hotspot-gtest” locally and Mach5 tier1,2,3


cheers