RFR: 8292916: Streamline LoaderConstraint purging [v3]

[Coleen Phillimore]

On Thu, 1 Sep 2022 12:44:39 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> The code to purge loader constraints walks through the class loader list of an unloaded class, and then asserts that the there are no leftovers. It can just directly remove the list of loaders without that walk.
>> 
>> Also I left the variable name 'probe' to help with diffs for [JDK-8291969](https://bugs.openjdk.org/browse/JDK-8291969) a little, but it's a bad variable name.
>> 
>> Tested with tier1-3 which contains jck tests.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Copy logging rather than passing name to remove_constraint.

Offline, Ioi and talked about this change and it's not correct.  You can have a klass in a constraint get unloaded, but the loader list can then refer to constraints for classes that haven't been resolved with that name, so the constraint should not be deleted in this case.

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PR: https://git.openjdk.org/jdk/pull/10023