RFR: 8335896: Source launcher should set TCCL

[Alan Bateman]

On Tue, 9 Jul 2024 10:52:46 GMT, Christian Stein <cstein at openjdk.org> wrote:

> Please review this change to set the context class loader of the current thread to the in-memory class loader when the `java` launcher is invoked in source mode. Having the source launcher set the TCCL to the in-memory classloader is benefical for scenarious depending on the TCCL being set to the application-loading loader.
> 
> For example, the single-argument taking [`ServiceLoader.load(Class)`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/ServiceLoader.html#load(java.lang.Class)) method creates "a new service loader for the given service type, using the current thread's [context class loader](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Thread.html#getContextClassLoader())."

src/jdk.compiler/share/classes/com/sun/tools/javac/launcher/SourceLauncher.java line 204:

> 202:             ClassLoader loader = context.newClassLoaderFor(parentLoader, firstClassName);
> 203:             firstClass = Class.forName(firstClassName, false, loader);
> 204:             Thread.currentThread().setContextClassLoader(loader);

Are you sure this it the right place? It might be, but seeing it in a try-catch is surprising. It should be set before the initializer for the main class runs, which might be here but checking.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/20097#discussion_r1678076491