Replace Unsafe classpath lookup#232
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Stop using sun.misc.Unsafe to read the app class loader internals in ClassLoaders.systemClassPaths() and switch to standard java.class.path parsing instead. This removes the terminal deprecation warning on newer JDKs while keeping the resolved classpath output unchanged. Observed warning: WARNING: A terminally deprecated method in sun.misc.Unsafe has been called WARNING: sun.misc.Unsafe::objectFieldOffset has been called by space.vectrix.ignite.util.ClassLoaders (file:/usr/bin/paper/ignite-launcher.jar) WARNING: Please consider reporting this to the maintainers of class space.vectrix.ignite.util.ClassLoaders WARNING: sun.misc.Unsafe::objectFieldOffset will be removed in a future release Add a regression test that compares the new implementation against the previous Unsafe-based lookup on JDK internal class loaders, and wire in the minimal JUnit 5 test configuration required for launcher tests. Verified with a direct JVM comparison of old vs. new output (`same=true`) and a successful `:ignite-launcher:test` run.
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Mar 24, 2026
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Looks good so far! Just a few changes I'd suggest. Let's also remove the unit tests for now, we can look at adding a full unit test suite in the future.
| final Field pathField = ucpField.getType().getDeclaredField("path"); | ||
| final long pathFieldOffset = (long) objectFieldOffsetMethod.invoke(unsafe, pathField); | ||
| final ArrayList<URL> path = (ArrayList<URL>) getObjectMethod.invoke(unsafe, ucpObject, pathFieldOffset); | ||
| final String separator = System.getProperty("path.separator", File.pathSeparator); |
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Just using File.pathSeparator would be good enough, don't need to grab it from the system property.
| final ArrayList<URL> path = (ArrayList<URL>) getObjectMethod.invoke(unsafe, ucpObject, pathFieldOffset); | ||
| final String separator = System.getProperty("path.separator", File.pathSeparator); | ||
| final List<URL> urls = new ArrayList<>(); | ||
| for(final String entry : classPath.split(java.util.regex.Pattern.quote(separator))) { |
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Lets not use regex here. We can simply do split(File.pathSeparator).
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What changed
sun.misc.Unsafefallback inClassLoaders.systemClassPaths()with standardjava.class.pathparsingUnsafe-based behavior on JDK internal class loadersWhy
Running the launcher on newer JDKs emits a terminal deprecation warning because Ignite calls
sun.misc.Unsafe::objectFieldOffsetwhile inspecting the application class loader internals. The new implementation removes that dependency while preserving the resolved classpath output.Observed warning:
Verification
same=true:ignite-launcher:testpassed successfullyNotes