8327257: [lworld] Tests are needed to stress class preloading with concurrent class loadings

[Arraying]

Hi all,

This change strengthens our Valhalla-specific classloading test suite and guards against regressions. An overview of the new changes is as follows:

• BigClassTreeClassLoader: a utility classloader that generates huge class trees on the fly. The idea is to generate a tree that is deep (lots of parent classes) and very wide (classes have lots of value classes as fields, which have value class fields, etc.).
• ConcurrentClassLoadingTest strains the classloading and preloading by classloading many classes at the same time.
• LoadableDescriptorsTest ensures that the LoadableDescriptors attribute can handle unexpected data. This may need to be revisited if https://bugs.openjdk.org/browse/JDK-8366907 changes the semantics.
• PreLoadCircularityTest ensures that preloading happens even when there are cycles (via inheritance, fields, and both).
• PreLoadDoesNotInitTest is a regression test that ensures preloading will not initialize a class.
• PreLoadFailuresDoNotImpactApplicationTest ensures that a flaky classloader during preloading will not cause crashes as long as the classloader can find the class when it is actually used.
• ValueClassInheritanceTest is a regression test that ensures one cannot have a value class inherit from something that's not an abstract value class.

---

Progress

• Change must not contain extraneous whitespace

Issue

• JDK-8327257: [lworld] Tests are needed to stress class preloading with concurrent class loadings (Bug - P4)

Reviewers

• David Simms (@MrSimms - Committer)

Reviewing

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/valhalla.git pull/1552/head

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[bridgekeeper]

👋 Welcome back phubner! 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]

@Arraying 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:

8327257: [lworld] Tests are needed to stress class preloading with concurrent class loadings

Reviewed-by: dsimms

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At the time when this comment was updated there had been 2 new commits pushed to the lworld branch:

• 3e84ee6: [lworld] One more workaround for JDK-8366668
• 320b11c: [lworld] Problem listing tests failing due to JDK-8366806

Please see this link for an up-to-date comparison between the source branch of this pull request and the lworld branch.
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[mlbridge]

Webrevs

• 02: Full - Incremental (d02d931b)
• 01: Full - Incremental (9df98b53)
• 00: Full (68324e4b)

[MrSimms]

Sorry I pushed the jdk-26+1 merge, meaning you'll need to flick major version (69 to 70).

[MrSimms]

Looks good

[Arraying]

Thanks for the review.

[Arraying]

/integrate

[openjdk]

@Arraying
Your change (at version d02d931) is now ready to be sponsored by a Committer.

[MrSimms]

/sponsor

[openjdk]

Going to push as commit 092078e.
Since your change was applied there have been 2 commits pushed to the lworld branch:

• 3e84ee6: [lworld] One more workaround for JDK-8366668
• 320b11c: [lworld] Problem listing tests failing due to JDK-8366806

Your commit was automatically rebased without conflicts.

[openjdk]

@MrSimms @Arraying Pushed as commit 092078e.

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