7195: GC confguration with GC Flags

[bric3]

This pull request proposes to display related garbage collector flags.

Motivation

When turning the GC flag knobs, it is useful to be able to quickly see
the GC configuration, however the GC configuration page only show 3
events, if one wants to have a look at flags he has to either check
the command line or inspect the JVM internal page to find relevant
GC flags. Therefore having these flags right there is useful to get
a quick picture of the current configuration.

Current limitations

1. At this time the selected flags depends on the GC algorithm which is
   derived from the name of the old collector name. This is simple,
   however it prevents to identify EpsilonGC because whose old
   collector name is SerialOld, which is the same as SerialGC.

2. There are some global flags in gc/shared/gc_globals.hpp that
   I didn't include as I didn't use most of them. I'm not sure these
   flags are seen much in the wild.

Remarks

As mentionned above the use of the OldCollector name may not be the
best choice, I would like to refactor this part to use the Use*GC
flags instead. I am a bit unsure at this time how to use the
existing API.

---

Progress

• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JMC-7195: GC confguration with GC Flags

Reviewers

• Marcus Hirt (@thegreystone - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jmc pull/230/head:pull/230
$ git checkout pull/230

Update a local copy of the PR:
$ git checkout pull/230
$ git pull https://git.openjdk.java.net/jmc pull/230/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 230

View PR using the GUI difftool:
$ git pr show -t 230

Using diff file

Download this PR as a diff file:
https://git.openjdk.java.net/jmc/pull/230.diff

[bridgekeeper]

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[bric3]

/signed

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[thegreystone]

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Copyright (c) 2018, 2021, Oracle and/or its affiliates. All rights reserved.

[mlbridge]

Webrevs

• 00: Full (ff0c91f8)

[thegreystone]

Sorry for the delay @bric3, and thank you your contribution! :)

[openjdk]

@bric3 This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

7195: GC confguration with GC Flags

Reviewed-by: hirt

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 18 new commits pushed to the master branch:

• 9829c20: 7236: Adding project specific settings to ignore forbidden references
• 278a95f: 7235: Some writer cleanup
• 9852c99: 7256: Use .jcheck/conf property to control version
• af9df26: 7201: JdkAttributes.OS_SWITCH_RATE does not work consistently across JFRs from different JDK versions.
• d708be3: 7164: Add support for hidden classes
• 8653337: 7241: Adjust main pom.xml to more align for 3th party builds
• 30223c7: 7124: Support the new JDK 16 allocation profiling event
• 917a95c: 7246: ClassCastException when opening heap dump
• 7732a7c: 7105: Unable to open graph-view if JMC is booted with JDK 8
• 033cc93: 6939: Time range indicator isn't updated when setting the time range
• ... and 8 more: https://git.openjdk.java.net/jmc/compare/acbc1e62eeb47c6cbb064f8a084c942ab0e656bd...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@thegreystone) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[bric3]

/integrate

[openjdk]

@bric3
Your change (at version ff0c91f) is now ready to be sponsored by a Committer.

[thegreystone]

/sponsor

[openjdk]

@thegreystone @bric3 Since your change was applied there have been 18 commits pushed to the master branch:

• 9829c20: 7236: Adding project specific settings to ignore forbidden references
• 278a95f: 7235: Some writer cleanup
• 9852c99: 7256: Use .jcheck/conf property to control version
• af9df26: 7201: JdkAttributes.OS_SWITCH_RATE does not work consistently across JFRs from different JDK versions.
• d708be3: 7164: Add support for hidden classes
• 8653337: 7241: Adjust main pom.xml to more align for 3th party builds
• 30223c7: 7124: Support the new JDK 16 allocation profiling event
• 917a95c: 7246: ClassCastException when opening heap dump
• 7732a7c: 7105: Unable to open graph-view if JMC is booted with JDK 8
• 033cc93: 6939: Time range indicator isn't updated when setting the time range
• ... and 8 more: https://git.openjdk.java.net/jmc/compare/acbc1e62eeb47c6cbb064f8a084c942ab0e656bd...master

Your commit was automatically rebased without conflicts.

Pushed as commit 39643ce.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.