8383856: Implementation of JEP 523: Make G1 the Default Garbage Collector in All Environments

[tschatzl]

Hi all,

please review this change of the default collector, making G1 the only default ever selected by ergonomics.

If G1 is not compiled in, the orginal logic to first try parallel and then serial has been maintained (which also necessitates keeping os::is_server_class_machine()).

Testing: gha, tier1-3, manually invoke the VM with various settings of maximum physical memory and available cpus (systemd-run/taskset) showing the expected behavior.

Thanks,
Thomas

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Progress

• Change must not contain extraneous whitespace
• Change requires CSR request JDK-8383863 to be approved
• Commit message must refer to an issue
• Change must be properly reviewed (2 reviews required, with at least 1 Reviewer, 1 Author)

Issues

• JDK-8383856: Implementation of JEP 523: Make G1 the Default Garbage Collector in All Environments (Enhancement - P4)
• JDK-8383863: JEP 523: Make G1 the Default Garbage Collector in All Environments (CSR)

Reviewers

• Stefan Karlsson (@stefank - Reviewer)
• Stefan Johansson (@kstefanj - Reviewer) Review applies to b59610dc
• Paul Hübner (@Arraying - Committer)

Reviewing

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Webrevs

• 01: Full - Incremental (96942793)
• 00: Full (b59610dc)

[Arraying]

Thanks! 🚀