disable threads

Author: zeitlinger

instrumentation/runtime-telemetry/runtime-telemetry-java8/library/src/main/java/io/opentelemetry/instrumentation/runtimemetrics/java8/Threads.java

@@ -57,7 +57,13 @@ public final class Threads {
 
   /** Register observers for java runtime class metrics. */
   public static List<AutoCloseable> registerObservers(OpenTelemetry openTelemetry) {
-    return INSTANCE.registerObservers(openTelemetry, !isJava9OrNewer());
+    return INSTANCE.registerObservers(openTelemetry, useThreads());
+  }
+
+  private static boolean useThreads() {
+    // GraalVM native image does not support ThreadMXBean yet
+    // see https://github.com/oracle/graal/issues/6101
+    return !isJava9OrNewer() || System.getProperty("org.graalvm.nativeimage.imagecode") != null;
   }
 
   private List<AutoCloseable> registerObservers(OpenTelemetry openTelemetry, boolean useThread) {