BTrace script which monitors sample cache access application (https://github.com/PiotrNowicki/BTrace-Cache-access-app)

CacheMonitorBTrace.java

package com.piotrnowicki.btrace;

import static com.sun.btrace.BTraceUtils.printArray;
import static com.sun.btrace.BTraceUtils.println;
import static com.sun.btrace.BTraceUtils.strcat;

import java.lang.ref.WeakReference;

import com.sun.btrace.AnyType;
import com.sun.btrace.BTraceUtils.Aggregations;
import com.sun.btrace.BTraceUtils.Strings;
import com.sun.btrace.aggregation.Aggregation;
import com.sun.btrace.aggregation.AggregationFunction;
import com.sun.btrace.annotations.BTrace;
import com.sun.btrace.annotations.Duration;
import com.sun.btrace.annotations.Export;
import com.sun.btrace.annotations.Kind;
import com.sun.btrace.annotations.Location;
import com.sun.btrace.annotations.OnMethod;
import com.sun.btrace.annotations.OnTimer;
import com.sun.btrace.annotations.ProbeClassName;
import com.sun.btrace.annotations.ProbeMethodName;
import com.sun.btrace.annotations.Property;
import com.sun.btrace.annotations.TargetMethodOrField;

// @BTrace means that this class will be used to define probes 
// and actions. All fields and methods must be static. 
// You can use only BTraceUtils methods.
@BTrace
@SuppressWarnings("unused")
public class CacheMonitorBTrace {

  // This field will be exported as a JStat counter.
  @Export
  private static long dataAccessed;

  // This field will be exported to the MBean server.
  @Property
  private static long dataCreated;

  @Property
  private static long cacheChecked;

  private static Aggregation methodDuration = Aggregations
            .newAggregation(AggregationFunction.AVERAGE);

 /**
  * We want to measure how long does the 
  * DataAcccesor#getData(-) method execution take.
  */
 @OnMethod(clazz = "com.piotrnowicki.btrace.DataAccessor", 
         method = "getData", 
         location = @Location(Kind.RETURN))
 public static void addMethodDuration(@Duration long duration) {
     Aggregations.addToAggregation(methodDuration, 
                                   duration / 1000);

     dataAccessed++;
 }

  /**
   * Invoked whenever WeakReference#get(-) is invoked from the 
   * DataAccessor#getData(-) method.
   */
  @OnMethod(clazz = "com.piotrnowicki.btrace.DataAccessor", 
          method = "getData", 
          location = @Location(value = Kind.CALL, 
                       clazz = "java.lang.ref.WeakReference", 
                       method = "get"))
  public static void cacheChecked(
          @TargetMethodOrField(fqn = true) String method) {
      println(strcat("Cache check invoked; method: ", method));

      cacheChecked++;
  }

  /**
   * Invoked when any method from DataAccessor class is entered.
   */
  @OnMethod(clazz = "com.piotrnowicki.btrace.DataAccessor", 
          method = "/.*/", 
          location = @Location(value = Kind.ENTRY))
  public static void dataAccessorMethodEntry(
                     @ProbeClassName String className,
                     @ProbeMethodName String probeMethod,
                     AnyType[] args) {
      println(Strings.strcat("Entered method: ", probeMethod));
      printArray(args);
  }

  /**
   * Invoked whenever new Data object is created from 
   * DataAccessor#getData(-) method.
   */
  @OnMethod(clazz = "com.piotrnowicki.btrace.DataAccessor", 
         method = "getData", 
         location = @Location(value = Kind.NEW, 
                        clazz = "com.piotrnowicki.btrace.Data"))
  public static void dataCreated() {
      dataCreated++;
  }

  /**
   * Invoked every 10 seconds - not a real probe.
   */
  @OnTimer(value = 10000)
  public static void printAvgMethodDuration() {
      Aggregations.printAggregation(
              "Average method duration (ms)", methodDuration);
  }
}

• Starting BTrace task
  ** Compiling the BTrace script ...
  !!! Error occured
  !!! Error occured

http://piotrnowicki.com/2012/05/btrace-a-simple-way-to-instrument-running-java-applications/

VisualVM version: 1.3.7
JDK version: 1.7.0

The problem is related with the version of BTrace. If you are using a version > 1.2 you should modify the script in this way (like explained here https://kenai.com/projects/btrace/pages/UserGuide).

package com.sun.btrace.samples;

import com.sun.btrace.AnyType;
import com.sun.btrace.BTraceUtils;
import com.sun.btrace.aggregation.Aggregation;
import com.sun.btrace.aggregation.AggregationFunction;
import com.sun.btrace.annotations.*;
import com.sun.btrace.annotations.Export;

import static com.sun.btrace.BTraceUtils.*;

// @BTrace means that this class will be used to define probes
// and actions. All fields and methods must be static.
// You can use only BTraceUtils methods.
@BTrace
class CacheMonitorBTrace {

    // This field will be exported as a JStat counter.
    @Export
    long dataAccessed;

    // This field will be exported to the MBean server.
    @Property
    long dataCreated;

    @Property
    long cacheChecked;

    Aggregation methodDuration = BTraceUtils.Aggregations.newAggregation(AggregationFunction.AVERAGE);

    /**
     * We want to measure how long does the
     * DataAcccesor#getData(-) method execution take.
     */
    @OnMethod(clazz = "com.piotrnowicki.btrace.DataAccessor", method = "getData", location = @Location(Kind.RETURN))
    void addMethodDuration(@Duration long duration) {
        BTraceUtils.Aggregations.addToAggregation(methodDuration, duration / 1000);
        dataAccessed++;
    }

    /**
     * Invoked whenever WeakReference#get(-) is invoked from the
     * DataAccessor#getData(-) method.
     */
    @OnMethod(clazz = "com.piotrnowicki.btrace.DataAccessor", method = "getData", location = @Location(value = Kind.CALL,
            clazz = "java.lang.ref.WeakReference", method = "get"))
    void cacheChecked(@TargetMethodOrField(fqn = true) String method) {
        println(Strings.strcat("Cache check invoked; method: ", method));
        cacheChecked++;
    }

    /**
     * Invoked when any method from DataAccessor class is entered.
     */
    @OnMethod(clazz = "com.piotrnowicki.btrace.DataAccessor", method = "/.*/", location = @Location(value = Kind.ENTRY))
    void dataAccessorMethodEntry(@ProbeClassName String className, @ProbeMethodName String probeMethod, AnyType[] args) {
        println(Strings.strcat("Entered method: ", probeMethod));
        printArray(args);
    }

    /**
     * Invoked whenever new Data object is created from
     * DataAccessor#getData(-) method.
     */
    @OnMethod(clazz = "com.piotrnowicki.btrace.DataAccessor", method = "getData", location = @Location(value = Kind.NEW, clazz = "com.piotrnowicki.btrace.Data"))
    void dataCreated() {
        dataCreated++;
    }

    /**
     * Invoked every 10 seconds - not a real probe.
     */
    @OnTimer(value = 10000)
    void printAvgMethodDuration() {
        Aggregations.printAggregation("Average method duration (ms)", methodDuration);
    }
}