I ran into some OOM problems with a very large parent classpath even when I set the parent to be ignored. I discovered that the following code in ClasspathFinder.java is not quite ignoring the parent.

                    final LogNode classloaderHandlerLog = classloaderURLLog == null ? null
                            : classloaderURLLog
                                    .log("Ignoring parent classloader " + classLoader + ", normally handled by "
                                            + classLoaderHandlerRegistryEntry.classLoaderHandlerClass.getName());
                    classLoaderHandlerRegistryEntry.findClasspathOrder(classLoader, ignoredClasspathOrder, scanSpec,
                            classloaderHandlerLog);

This reads everything in the parent for the where the user is ignoring parents, but scanning the entire java.class.path anyway (?). There are a number of settings under which the retained information is never used, and this just becomes a memory usage liability. (PR shortly)

As commentary, I think I would find it confusing to sort out the case where a class on the class path was loaded by the parent and then mysteriously didn't show up when I scanned the java.class.path... so I find that use case a bit dubious to begin with, but I imagine someone must have it.