RFR: JDK-8325139: JFR SwapSpace event - add free swap space information on Linux when running in a container environment

Thu Feb 22 15:37:13 UTC 2024

The JFR SwapSpace event (added by [JDK-8324287](https://bugs.openjdk.org/browse/JDK-8324287)) has been added but in a Linux containerized environment we currently just report -1, this should be enhanced. There is already some code in the mbeans (but in Java) that does something similar .

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Commit messages:
 - JDK-8325139

Changes: https://git.openjdk.org/jdk/pull/17966/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17966&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8325139
  Stats: 58 lines in 8 files changed: 56 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/17966.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17966/head:pull/17966

PR: https://git.openjdk.org/jdk/pull/17966