The profile package contains the api to implement an profiler for jruby. In the sub-package builtin you can find the profiler implementation shipped with jruby. To implement your own profiler implement the ProfilingService interface, add your implementation to the classpath an add the command line argument --profile.service my.impl.class Example Profiling Service Impl. 
public class MyProfiler implements ProfilingService {
 private final ConcurrentMap methods = new ConcurrentHashMap(1000);
 public ProfileCollection newProfileCollection(ThreadContext threadContext) {
   return new MyCollection();
 }
 public MethodEnhancer newMethodEnhancer(Ruby ruby) {
   return new MyMethodEnhancer();
 }
 public ProfileReporter newProfileReporter(ThreadContext threadContext) {
   return new MyReporter();
 }
 private class MyCollection implements ProfileCollection {
   private long serial;
   public void profileEnter(long method) {
     this.serial = method;
   }
   public void profileExit(long method, long time) {
     String name = methods.get(serial);
     serial = method;
     System.out.println(name + ": " + (System.nanoTime() - time));
   }
 }
 private class MyMethodEnhancer implements MethodEnhancer {
   public DynamicMethod enhance(String name, DynamicMethod delegate) {
     if ( isMyApp( delegate ) ) {
       methods.putIfAbsent(delegate.getSerialNumber(), name);
       return new ProfilingDynamicMethod(delegate);
     } else {
       return delegate;
     }
   }
   private boolean isMyApp( DynamicMethod method ) {
     //if( delegate.getRealMethod() instanceof PositionAware && ((PositionAware)delegate.getRealMethod()).getFile().contains(""))
     return method.getRealMethod().getImplementationClass().getId().startsWith("MyApp::");
   }
 }
 private static class MyReporter implements ProfileReporter {
   public void report(ProfileCollection profileCollection) {
     MyCollection collection = (MyCollection) profileCollection;
     // do nothing
   }
 }
}

Author:
Andre Kullmann/**
 * The profile package contains the api to implement an profiler for jruby.
 * In the sub-package builtin you can find the profiler implementation shipped with jruby.
 * To implement your own profiler implement the {@link org.jruby.runtime.profile.ProfilingService ProfilingService}
 * interface, add your implementation to the classpath an add the command line argument --profile.service my.impl.class
 *
 * Example Profiling Service Impl.
 *
 * <pre>
 *public class MyProfiler implements ProfilingService {
 *
 *  private final ConcurrentMap<Long, String> methods = new ConcurrentHashMap<Long, String>(1000);
 *
 *  public ProfileCollection newProfileCollection(ThreadContext threadContext) {
 *    return new MyCollection();
 *  }
 *
 *  public MethodEnhancer newMethodEnhancer(Ruby ruby) {
 *    return new MyMethodEnhancer();
 *  }
 *
 *  public ProfileReporter newProfileReporter(ThreadContext threadContext) {
 *    return new MyReporter();
 *  }
 *
 *  private class MyCollection implements ProfileCollection {
 *
 *    private long serial;
 *
 *    public void profileEnter(long method) {
 *      this.serial = method;
 *    }
 *
 *    public void profileExit(long method, long time) {
 *      String name = methods.get(serial);
 *      serial = method;
 *      System.out.println(name + ": " + (System.nanoTime() - time));
 *    }
 *  }
 *
 *  private class MyMethodEnhancer implements MethodEnhancer {
 *
 *    public DynamicMethod enhance(String name, DynamicMethod delegate) {
 *      if ( isMyApp( delegate ) ) {
 *        methods.putIfAbsent(delegate.getSerialNumber(), name);
 *        return new ProfilingDynamicMethod(delegate);
 *      } else {
 *        return delegate;
 *      }
 *    }
 *
 *    private boolean isMyApp( DynamicMethod method ) {
 *      //if( delegate.getRealMethod() instanceof PositionAware && ((PositionAware)delegate.getRealMethod()).getFile().contains(""))
 *      return method.getRealMethod().getImplementationClass().getId().startsWith("MyApp::");
 *    }
 *  }
 *
 *  private static class MyReporter implements ProfileReporter {
 *
 *    public void report(ProfileCollection profileCollection) {
 *      MyCollection collection = (MyCollection) profileCollection;
 *      // do nothing
 *    }
 *  }
 *
 *}
 * </pre>
 *
 * @author Andre Kullmann
 */
@Deprecated
package org.jruby.runtime.profile;