RFR (XS): 8076541: Parallel GC registers Java heap twice to NMT

[Thomas Schatzl]

Hi all,

  can I have reviews for the following tiny change that fixes redundant
method calls in parallel scavenge?

ParallelScavengeHeap::initialize() calls
MemTracker::record_virtual_memory_type() although
Universe::reserve_heap() via the ReservedHeapSpace constructor already
does that.

Also, later it checks whether the the heap has been reserved or not, and
exits the VM if necessary. Universe::reserve_heap() already does that.

CR:
https://bugs.openjdk.java.net/browse/JDK-8076541

Webrev:
http://cr.openjdk.java.net/~tschatzl/8076541/webrev/

Testing:
jprt, manual checking of NMT output to contain ReservedHeapSpace
reservation for all gcs. Checked with ulimit -v that all collectors
print the "Could not reserve enough space for XYKB object heap" message.

Thanks,
  Thomas