src/java.base/share/classes/java/lang/Runtime.java

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  import java.io.*;
  import java.util.StringTokenizer;
  import sun.reflect.CallerSensitive;
  import sun.reflect.Reflection;
+ import jdk.internal.HotSpotIntrinsicCandidate;
  
  /**
   * Every Java application has a single instance of class
   * {@code Runtime} that allows the application to interface with
   * the environment in which the application is running. The current
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          }
          ClassLoader.loadLibrary(fromClass, libname, false);
      }
  
      /** 
+      * Indicates that the caller is momentarily unable to progress, until the
+      * occurrence of one or more actions on the part of other activities.  By
+      * invoking this method within each iteration of a spin-wait loop construct,
+      * the calling thread indicates to the runtime that it is busy-waiting. The runtime
+      * may take action to improve the performance of invoking spin-wait loop
+      * constructions.
+      */
+     @HotSpotIntrinsicCandidate
+     public static void onSpinWait() { }
+ 
+     /**
       * Creates a localized version of an input stream. This method takes
       * an {@code InputStream} and returns an {@code InputStream}
       * equivalent to the argument in all respects except that it is
       * localized: as characters in the local character set are read from
       * the stream, they are automatically converted from the local