8368080: G1: Unnecessary initialization of G1CMTask's mark stats table

[tschatzl]

Hi all,

please review this tiny change that leaves out resetting the mark stat caches at startup.

This has some (somewhat tiny, depending on heap size and number of threads) positive impact on startup time.

Testing: tier1-5, gha

Thanks,
Thomas

---

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-8368080: G1: Unnecessary initialization of G1CMTask's mark stats table (Enhancement - P4)

Reviewers

• Ivan Walulya (@walulyai - Reviewer)
• Aleksey Shipilev (@shipilev - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/27390/head:pull/27390
$ git checkout pull/27390

Update a local copy of the PR:
$ git checkout pull/27390
$ git pull https://git.openjdk.org/jdk.git pull/27390/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 27390

View PR using the GUI difftool:
$ git pr show -t 27390

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/27390.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back tschatzl! 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]

@tschatzl 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:

8368080: G1: Unnecessary initialization of G1CMTask's mark stats table

Reviewed-by: iwalulya, shade

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 31 new commits pushed to the master branch:

• 4445463: 8368086: G1: Use ThreadsClaimTokenScope in G1CMRemarkTask
• f10fbe1: 8368072: Remove redundant arguments of MarkingNMethodClosure
• 258fcf9: 8367987: Memory leak in MemBaseline: Must delete _vma_allocations
• ... and 28 more: https://git.openjdk.org/jdk/compare/28879d3d03ca6e8ea68a6063da349d83310b22ce...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]

@tschatzl 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 (08f7dc94)

[shipilev]

Question: There is a use of G1RegionMarkStatsCache in G1CMTask (responsible for concurrent marking as well?) -- shouldn't the reset happen on that path as well? If so, and testing did not caught it, there should be some sort of assert somewhere?

[walulyai]

Question: There is a use of G1RegionMarkStatsCache in G1CMTask (responsible for concurrent marking as well?) -- shouldn't the reset happen on that path as well? If so, and testing did not caught it, there should be some sort of assert somewhere?

That reset was already happening in G1ConcurrentMark::reset().

[shipilev]

OK then!

[tschatzl]

Thanks @walulyai @shipilev for your reviews
/integrate

[openjdk]

Going to push as commit 2e99ed6.
Since your change was applied there have been 59 commits pushed to the master branch:

• 3e5094e: 8366865: Allocation GC Pauses Triggered after JVM has started shutdown
• 360b6af: 8364657: Crash for SecureRandom.generateSeed(0) on Windows x86-64
• 47ed1a8: 8368213: ZGC: Cleanup dead code, unimplemented declarations, unused private fields
• ... and 56 more: https://git.openjdk.org/jdk/compare/28879d3d03ca6e8ea68a6063da349d83310b22ce...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit 2e99ed6.

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