[jdk8u-dev] RFR: 8151460: Metaspace counters can have inconsistent values

[Thomas Stuefe]

To reduce intermittent errors from TestPerfCountersAndMemoryPools, I'd like to backport "8151460: Metaspace counters can have inconsistent values".

This does not backport cleanly since JEP 280 [1] modified the test, and I won't backport that one of course. Therefore I also added the test-specific fix JEP 280 did (https://github.com/openjdk/jdk8u-dev/commit/24773b47512b522c9bfa346559a34138d900b77e).

Tests: I manually ran gc/metaspace jtreg tests on Linux x64 with fastdebug and release builds.

[1] https://bugs.openjdk.org/browse/JDK-8148483

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Commit messages:
 - JDK-8151460: Metaspace counters can have inconsistent values
 - JEP 280 portion

Changes: https://git.openjdk.org/jdk8u-dev/pull/301/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=301&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8151460
  Stats: 21 lines in 2 files changed: 12 ins; 1 del; 8 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/301.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/301/head:pull/301

PR: https://git.openjdk.org/jdk8u-dev/pull/301