8364282: ZGC: Improve ZPageAllocation JFR event sending

[jsikstro]

Hello,

This is a follow up to JDK-8350441, improving on how the ZPageAllocation JFR event is sent.

The starting time for the event is measured separately from creating a local event variable (EventZPageAllocation). This means it is better to use the anonymous EventZPageAllocation::commit rather than creating an event and sending that event, which would record the starting time again, unnecessarily.

Additionally, if the event is not enabled (either specifically or if JFR is disabled), we should not waste time sampling statistics for the event.

Testing:

• Oracle's tier1-4

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8364282: ZGC: Improve ZPageAllocation JFR event sending (Enhancement - P4)

Reviewers

• Stefan Karlsson (@stefank - Reviewer)
• Axel Boldt-Christmas (@xmas92 - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/26534/head:pull/26534
$ git checkout pull/26534

Update a local copy of the PR:
$ git checkout pull/26534
$ git pull https://git.openjdk.org/jdk.git pull/26534/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 26534

View PR using the GUI difftool:
$ git pr show -t 26534

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/26534.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back jsikstro! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@jsikstro 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:

8364282: ZGC: Improve ZPageAllocation JFR event sending

Reviewed-by: stefank, aboldtch

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 23 new commits pushed to the master branch:

• a2e86ff: 8364037: Sort share includes: adlc, libadt, metaprogramming
• e2feff8: 8355177: Speed up StringBuilder::append(char[]) via Unsafe::copyMemory
• 16da81e: 8360817: [ubsan] zDirector select_worker_threads - outside the range of representable values issue
• ... and 20 more: https://git.openjdk.org/jdk/compare/28297411b19551dd8585165200f5f8158f3d5bb3...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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[openjdk]

@jsikstro The following label will be automatically applied to this pull request:

• hotspot-gc

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 00: Full (b61fbaa5)

[jsikstro]

Thank you for the reviews! @stefank @xmas92
/integrate

[openjdk]

Going to push as commit b9f7cae.
Since your change was applied there have been 29 commits pushed to the master branch:

• ebb7f5d: 8364111: InstanceMirrorKlass iterators should handle CDS and hidden classes consistently
• 05c63e8: 8361524: [XWayland] possible JavaFX interop hang
• 559795b: 8362501: Update test/hotspot/jtreg/applications/jcstress/README
• ... and 26 more: https://git.openjdk.org/jdk/compare/28297411b19551dd8585165200f5f8158f3d5bb3...master

Your commit was automatically rebased without conflicts.

[openjdk]

@jsikstro Pushed as commit b9f7cae.

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