Fix faulty class loader

[dmlloyd]

The class loader as it is written will always delegate to the parent class loader first looking for the bytes of the class. This is very bad if the parent class loader happens to have the class, as is the case when a JBang library overlaps with a Quarkus one. This results in the RuntimeLauncherClassLoader defining the class as if it found it in its own set of resources, however the class bytes actually came from the JBang class loader (all of the class loaders involved are parent-first, so it goes right up to the top).

A class loader should never search for class resources outside of its own search path (particularly in parent class loaders). So, the fix is to look for the ide-launcher-res resource exclusively. If it's not found there, we can safely fail because the class loader is parent-first, so there'd be nothing left to search anyway.

Should fix #43648, which should be rebased after this. Fixes #43681.

[gastaldi]

Nice catch @dmlloyd !

[quarkus-bot]

Status for workflow Quarkus CI

This is the status report for running Quarkus CI on commit aa6bf6c.

Failing Jobs

Status	Name	Step	Failures	Logs	Raw logs	Build scan
✔️	JVM Tests - JDK 17			Logs	Raw logs	🔍
✖	JVM Tests - JDK 21	Build	Failures	Logs	Raw logs	🔍

Full information is available in the Build summary check run.
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Failures

⚙️ JVM Tests - JDK 21 #

- Failing: extensions/reactive-mysql-client/deployment 
! Skipped: integration-tests/hibernate-reactive-mariadb integration-tests/hibernate-reactive-mysql integration-tests/hibernate-reactive-mysql-agroal-flyway and 1 more

📦 extensions/reactive-mysql-client/deployment

✖ io.quarkus.reactive.mysql.client.MySQLPoolProducerTest. - History - More details - Source on GitHub

java.lang.RuntimeException: 
java.lang.RuntimeException: io.quarkus.builder.BuildException: Build failure: Build failed due to errors
	[error]: Build step io.quarkus.datasource.deployment.devservices.DevServicesDatasourceProcessor#launchDatabases threw an exception: java.lang.RuntimeException: org.testcontainers.containers.ContainerLaunchException: Container startup failed for image docker.io/mysql:8.4
	at io.quarkus.datasource.deployment.devservices.DevServicesDatasourceProcessor.startDevDb(DevServicesDatasourceProcessor.java:367)
	at io.quarkus.datasource.deployment.devservices.DevServicesDatasourceProcessor.launchDatabases(DevServicesDatasourceProcessor.java:121)
	at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:733)
	at io.quarkus.deployment.ExtensionLoader$3.execute(ExtensionLoader.java:856)
	at io.quarkus.builder.BuildContext.run(BuildContext.java:256)

[maxandersen]

very nice find - any chance this could explain some of the classloader leaks we've been battling with ?

[gsmet]

any chance this could explain some of the classloader leaks we've been battling with ?

I don't think so. IIRC, this class loader is only used for IDE launching and JBang.
I'm not exactly sure why we use it for running a JBang script outside of the IDE though.
I would have expected this integration to use the standard class loading.