RFR: 8268443: ParallelGC Full GC should use parallel WeakProcessor

Wed Jun 9 20:55:29 UTC 2021

Simple change of making weak oops processing in Full GC cycles parallel for Parallel collector.

Tested: running benchmarks with `gc+phases=debug` and confirm the `Weak Processing` time in Full GCs becomes shorter.

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Commit messages:
 - weak_oops

Changes: https://git.openjdk.java.net/jdk/pull/4444/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4444&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268443
  Stats: 4 lines in 1 file changed: 3 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4444.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4444/head:pull/4444

PR: https://git.openjdk.java.net/jdk/pull/4444