8387997: [lworld] Add JVMTI general spec clarification about value objects by sspitsyn · Pull Request #2634 · openjdk/valhalla

sspitsyn · 2026-07-09T03:44:27Z

This update is for repo-valhalla pre-integration. It adds a special intro section to the jvmti.xml with a general clarification related to value objects. Also, it fixes a couple of small typos.

Testing: N/A

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Issue

JDK-8387997: [lworld] Add JVMTI general spec clarification about value objects (Enhancement - P2)

Reviewers

David Holmes (@dholmes-ora - Committer)
Chris Plummer (@plummercj - Committer)

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David Holmes <dholmes@openjdk.org>

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$ git fetch https://git.openjdk.org/valhalla.git pull/2634/head:pull/2634
$ git checkout pull/2634

Update a local copy of the PR:
$ git checkout pull/2634
$ git pull https://git.openjdk.org/valhalla.git pull/2634/head

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$ git pr checkout 2634

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bridgekeeper · 2026-07-09T03:45:46Z

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

openjdk · 2026-07-09T03:45:47Z

@sspitsyn 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:

8387997: [lworld] Add JVMTI general spec clarification about value objects

Co-authored-by: David Holmes <dholmes@openjdk.org>
Reviewed-by: dholmes, cjplummer

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 61 new commits pushed to the lworld branch:

db84603: 8388445: [lworld] update ProblemList-Xcomp.txt entries from 8378071 to 8388438
a1d8258: 8387875: [lworld] Provide value-class-preview.md file
53b4a9e: 8388261: [lworld] javac creates early_larval_frame and ACC_STRICT_INIT in record non-preview class files
... and 58 more: https://git.openjdk.org/valhalla/compare/23a199ffb1c27605257f1be6d8a5b8bcfa85e25d...lworld

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 lworld branch, type /integrate in a new comment.

mlbridge · 2026-07-09T03:51:38Z

Webrevs

sspitsyn · 2026-07-10T09:14:52Z

/contributor add @dholmes-ora

openjdk · 2026-07-10T09:16:01Z

@sspitsyn
Contributor David Holmes <dholmes@openjdk.org> successfully added.

sspitsyn · 2026-07-17T02:26:05Z

I've made another update according to the offline agreement. There is also a minor tweak in the "Object Tags" section.

dholmes-ora

Looks good. One suggested update.

dholmes-ora · 2026-07-17T02:34:27Z

      When preview features are enabled, the Object Free event is only sent for tagged
      <externallink id="jni/functions.html#hasidentity">identity objects</externallink>.
-      <b>The event is not sent for tagged values objects.</b>
+      <b>The event is not sent for tagged value objects.</b>


Suggested change

<b>The event is not sent for tagged value objects.</b>

<b>The event is not sent for tagged value objects because they are kept alive while tagged.</b>

To be consistent with earlier change.

We have discussed with you that this is confusing as the lifecycle of value objects is not defined. My move is in opposite direction. It is to remove this: "because they are kept alive while tagged."

sspitsyn · 2026-07-17T05:50:58Z

David, thank you for review!

dholmes-ora

Update looks good. Thanks

dholmes-ora · 2026-07-17T06:30:14Z

Aside: you should add JVMTI to the issue synopsis. Thanks

sspitsyn · 2026-07-17T08:09:53Z

Aside: you should add JVMTI to the issue synopsis. Thanks

Fixed now.

plummercj

Looks good.

AlanBateman · 2026-07-20T15:50:34Z

+    a Java object that does not have identity. Such differences in behavior are described
+    by the individual functions and events where they apply.
+    <p/>
+    In summary, tags for value objects use value equality semantics, and


I think this is tricky to word as tags are (jlong) values. While more verbose, I wonder if it should be something like "Object tags are jlong values that a JVMTI agent can associate with an object. JVMTI allows a value object to be tagged despite the object having no identity. Consequently, the tag is a jong value associated with the object's fields rather than its identity.". Having it link to the "Object Tags" section would help too. Alternatively, we could beef up the "Object Tags" section so that this overview/intro section just links without doing into any details except to highlight that value objects can be tagged but ObjectFree events are only sent for tagged identity objects.

Good suggestions, thanks. I'll try to update as suggested. I like the alternative suggestion as well but it can be a little bit more tricky.

@AlanBateman There was a request to finalize the SVC CSR now. So, I'll integrate this now as is, and we can incorporate your suggestion later,

Okay, and I assume you'll create a JBS issue for the follow-up.

Filed this issue:
8388540 [lworld] Need minor tweak in JVMTI intro section on value objects

Will publish a PR soon.

sspitsyn · 2026-07-20T21:14:49Z

David and Chris, thank you for review!

sspitsyn · 2026-07-20T21:14:57Z

/integrate

openjdk · 2026-07-20T21:16:18Z

Going to push as commit 87f1ae9.
Since your change was applied there have been 62 commits pushed to the lworld branch:

a0662f9: 8388113: [lworld] JDI and JDWP spec update: ObjectReference summary, Value class clarification, strict field initialization clarification
db84603: 8388445: [lworld] update ProblemList-Xcomp.txt entries from 8378071 to 8388438
a1d8258: 8387875: [lworld] Provide value-class-preview.md file
... and 59 more: https://git.openjdk.org/valhalla/compare/23a199ffb1c27605257f1be6d8a5b8bcfa85e25d...lworld

Your commit was automatically rebased without conflicts.

openjdk · 2026-07-20T21:16:31Z

@sspitsyn Pushed as commit 87f1ae9.

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

8387997: [lworld] Add general spec clarification about value objects

5eb982a

openjdk Bot added the rfr Pull request is ready for review label Jul 9, 2026

sspitsyn added 2 commits July 8, 2026 20:53

review: minor correction

e70c0b8

review: one more minor tweak

d68386a

dholmes-ora reviewed Jul 9, 2026

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Comment thread src/hotspot/share/prims/jvmti.xml Outdated

Comment thread src/hotspot/share/prims/jvmti.xml Outdated

review: simplify general clarification about value objects

caf47a2

review: reconsidered again; small tweak for onject tagging spec

cfff443

dholmes-ora approved these changes Jul 17, 2026

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openjdk Bot added the ready Pull request is ready to be integrated label Jul 17, 2026

review: update with tweaks suggested by David

38765ed

dholmes-ora approved these changes Jul 17, 2026

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sspitsyn changed the title ~~8387997: [lworld] Add general spec clarification about value objects~~ 8387997: [lworld] JVMTI Add general spec clarification about value objects Jul 17, 2026

openjdk Bot removed the ready Pull request is ready to be integrated label Jul 17, 2026

sspitsyn changed the title ~~8387997: [lworld] JVMTI Add general spec clarification about value objects~~ 8387997: [lworld] Add JVMTI general spec clarification about value objects Jul 17, 2026

openjdk Bot added the ready Pull request is ready to be integrated label Jul 17, 2026

plummercj approved these changes Jul 17, 2026

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AlanBateman reviewed Jul 20, 2026

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openjdk Bot added the integrated Pull request has been integrated label Jul 20, 2026

openjdk Bot closed this Jul 20, 2026

openjdk Bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Jul 20, 2026

	<b>The event is not sent for tagged value objects.</b>
	<b>The event is not sent for tagged value objects because they are kept alive while tagged.</b>

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