8202447: Fix unloading_occurred to mean unloading_occurred Summary: nmethod unloading does not need to test for jvmti to set unloading_occurred, nor do we need to clean weak Klasses in metadata if unloading does not occur. Reviewed-by: sspitsyn, rehn

8199067: [REDO] NMT: Enhance thread stack tracking Summary: Precise thread stack tracking on Linux and Windows Reviewed-by: stuefe, coleenp

8202021: Improve variable naming in ReferenceProcesso Reviewed-by: sangheki, sjohanss

8202018: Move card table clear before enqueuing pending references Summary: Move card table clearing in preparation of removal of the Reference enqueue phase. Reviewed-by: sangheki, sjohanss

8201640: Use _ref_processor_* member variables directly in G1CollectedHeap Reviewed-by: sjohanss

8201492: Properly implement non-contiguous generations for Reference discovery Summary: Collectors like G1 implementing non-contiguous generations previously used an inexact but conservative area for discovery. Concurrent and STW reference processing could discover the same reference multiple times, potentially missing referents during evacuation. So these collectors had to take extra measures while concurrent marking/reference discovery has been running. This change makes discovery exact for G1 (and any collector using non-contiguous generations) so that concurrent discovery and STW discovery discover on strictly disjoint memory areas. This means that the mentioned situation can not occur any more, and extra work is not required any more too. Reviewed-by: kbarrett, sjohanss

8195002: Fix test/hotspot/jtreg/gtest/GTestWrapper.java on Alpine/Musl Reviewed-by: stuefe, clanger, mikael

8202575: Remove java/lang/String/nativeEncoding/StringPlatformChars.java from ProblemList Reviewed-by: alanb