Withdrawn: 8321698: JFR asserts in write_classloader: failed invariant

[Markus Grönlund]

On Thu, 21 Dec 2023 17:47:34 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

> Greetings,
> 
> I have reviewed the JFR tagging mechanism, which lacks proper transitivity in certain situations. For example, when tagging a PackageEntry or a ModuleEntry, no tag information is set for the ModuleEntry's CLD and its class_loader_klass. The assert then fires when writing the CLD of a ModuleEntry, should its CLD not have been tagged by some other means (some other direct usage).
> 
> The tagging must, in general, become deeper than what is done today, i.e. it must cover the transitive closure of a Klass, which involves two branches:
> 
> 1) Klass -> CLD -> class_loader_klass
> 2) Klass -> PackageEntry -> ModuleEntry -> CLD -> class_loader_klass
> 
> A Klass under its closure can be treated as a node in a binary tree. Its closure (subtree) is covered by writing and tagging of artifacts using preorder traversal by recursing its CLD klasses.
> 
> Testing: jdk_jfr, stress testing
> 
> Thanks
> Markus

This pull request has been closed without being integrated.

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PR: https://git.openjdk.org/jdk/pull/17177