RFR: 8366040: Change URL.lookupViaProviders to use ScopedValue to detect recursive lookup

[Alan Bateman]

On Fri, 3 Oct 2025 16:38:50 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> Replace `ThreadTracker` usage in `java.net.URL` with `ScopedValue` and add a test.
>
> src/java.base/share/classes/java/net/URL.java line 1402:
> 
>> 1400:             throw new Error("Circular loading of URL stream handler providers detected");
>> 1401:         }
>> 1402:         return ScopedValue.where(IN_LOOKUP, true).call(() -> {
> 
> We should never reach here if the VM is not booted, or if the protocol is `file:` or `jrt:` - so it may be safe to use a lambda. The alternative would be to use an anonymous class and create a `new Runnable() { ... }` but it's probably not needed.

The changes to URL look okay but good to run any startup benchmarks to check startup performance.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/27623#discussion_r2402698820