apache/druid · warning · java.lang.UnsupportedOperationException

Cleaning is not support on this platform, because internal…

Error message

Cleaning is not support on this platform, because internal Java APIs are not compatible with this Druid version

What it means

Cleaners.takeMeToTheCleaners builds a Cleaner abstraction over JDK internals (java.lang.ref.Cleaner on 9+, or a Java 8 fallback). If no compatible cleaning API can be found via reflection, it throws this UnsupportedOperationException. Buffer cleaning (eager deallocation) is unsupported on the current JVM.

Solutions

Run on a standard, supported HotSpot OpenJDK (8 or 11+ per Druid's compatibility matrix).
Avoid --illegal-access=deny style flags or remove module restrictions blocking jdk.internal.ref access.
Catch UnsupportedOperationException at call sites (see Cleaners.register) and fall back to GC-based cleanup.

Example fix

// before
Cleaners.register(obj, cleanupRunnable);
// after
try {
  Cleaners.register(obj, cleanupRunnable);
} catch (UnsupportedOperationException e) {
  // cleaner unsupported; cleanup happens at GC
}

Defensive patterns

Strategy: try-catch

Try / catch

try {
  Cleanable c = Cleaners.register(obj, action);
} catch (UnsupportedOperationException e) {
  // cleaner unsupported on this JVM; rely on GC/close
}

Prevention

Pin deployments to supported JDK vendors/versions
Avoid jlink images that drop java.base internals
Never rely solely on cleaners for correctness of cleanup

When it happens

Trigger: Static initialization of Cleaners on a JVM where neither jdk.internal.ref.Cleaner (Java 9+ path) nor the Java 8 sun.misc path can be resolved, e.g. non-HotSpot JVMs, heavily restricted module settings, or stripped JDK images.

Common situations: Running Druid on unusual/locked-down Java runtimes; custom minimal JRE images (jlink) missing java.base internals; JVM vendors blocking deep reflection; the first use of Cleaners-dependent code triggering static init.

Understand the failure class

Background: "unsupported platform" / "not supported on this platform" errors: what they mean and how to fix them — this error's family across 47 libraries.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/e1dc5dcf10c046a0. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/java/util/common/Cleaners.java:66

      exception = e;
    }
    if (cleaner != null) {
      CLEANER = cleaner;
      CLEANER_NOT_SUPPORTED_EXCEPTION = null;
    } else {
      CLEANER = null;
      CLEANER_NOT_SUPPORTED_EXCEPTION = exception;
    }
  }

  private static Cleaner takeMeToTheCleaners()
  {
    final MethodHandles.Lookup lookup = MethodHandles.lookup();
    try {
      return lookupCleaner(lookup);
    }
    catch (ReflectiveOperationException | RuntimeException e) {
      throw new UnsupportedOperationException("Cleaning is not support on this platform, because internal " +
                                              "Java APIs are not compatible with this Druid version", e);
    }
  }

  private static Cleaner lookupCleaner(MethodHandles.Lookup lookup) throws ReflectiveOperationException
  {
    Class<?> cleaner = Class.forName("java.lang.ref.Cleaner");
    Class<?> cleanable = Class.forName("java.lang.ref.Cleaner$Cleanable");

    MethodHandle create = lookup.findStatic(cleaner, "create", MethodType.methodType(cleaner));

    Object theCleaner;
    try {
      theCleaner = create.invoke();
    }
    catch (Throwable t) {
      throw new RuntimeException("Unable to create cleaner", t);
    }

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