8354929: ZGC: Update collection stats while holding page allocator lock

[kstefanj]

Please review this change to restructure some code in the mark start pause to do updates while holding the lock.

Summary
We currently update the collection high and low used values during the mark start pause without taking the page allocator lock. This is fine since it is read atomically, but consistency verification in this code requires the lock to be held. We later in the pause take the lock to get the current statistics, this change moves the update code to also happen while holding the lock.

I've renamed reset_statistics() to update_collection_stats() to better match what it actually does and made it private.

Testing
Mach5 tier1-5

---

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-8354929: ZGC: Update collection stats while holding page allocator lock (Enhancement - P4)

Reviewers

• Stefan Karlsson (@stefank - Reviewer)
• Thomas Schatzl (@tschatzl - Reviewer) Review applies to b8966d36
• Axel Boldt-Christmas (@xmas92 - Reviewer) Review applies to b8966d36

Reviewing

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[bridgekeeper]

👋 Welcome back sjohanss! 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]

@kstefanj 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:

8354929: ZGC: Update collection stats while holding page allocator lock

Reviewed-by: stefank, tschatzl, 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 98 new commits pushed to the master branch:

• 2f7806f: 8355034: [JVMCI] assert(static_cast(_jvmci_data_size) == align_up(compiler->is_jvmci() ? jvmci_data->size() : 0, oopSize)) failed: failed: 104 != 16777320
• a55ccd2: 8352905: Open some JComboBox bugs 1
• 33bdc80: 8355241: Move NativeDialogToFrontBackTest.java PL test to manual category
• ... and 95 more: https://git.openjdk.org/jdk/compare/36864a2a08b5b64e63a9265d595ba7fb608994cb...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]

@kstefanj 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

• 02: Full - Incremental (1dc0beb5)
• 01: Full - Incremental (b8966d36)
• 00: Full (473bdff2)

[stefank]

Looks good. I've add a couple of suggestions for blank lines.

[xmas92]

lgtm. Just a comment about the assert message.

[kstefanj]

Thanks for the reviews @stefank, @xmas92 and @tschatzl

/integrate

[openjdk]

Going to push as commit 50358d1.
Since your change was applied there have been 102 commits pushed to the master branch:

• 367bcc5: 8353445: Open source several AWT Menu tests - Batch 1
• 7eab2d9: 8354095: Open some JTable bugs 5
• 0b2a2f3: 8353685: Open some JComboBox bugs 4
• ... and 99 more: https://git.openjdk.org/jdk/compare/36864a2a08b5b64e63a9265d595ba7fb608994cb...master

Your commit was automatically rebased without conflicts.

[openjdk]

@kstefanj Pushed as commit 50358d1.

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