public class InstanceCounter {
  public static void load() {
    ClassInjector.UsingUnsafe.ofBootLoader().injectRaw(Collections.singletonMap("foo.bar.BootstrapState", readBytes(InstanceCounter.class.getClassLoader().getResource("foo/bar/BootstrapState.class"))));
    new AgentBuilder.Default()
      .ignore(none())
      .disableClassFormatChanges()
      .with(RedefinitionStrategy.RETRANSFORMATION)
      .with(InitializationStrategy.NoOp.INSTANCE)
      .with(TypeStrategy.Default.REDEFINE)
    .type(any())
      .transform(new Transformer() {
        @Override
        public Builder<?> transform(final Builder<?> builder, final TypeDescription typeDescription, final ClassLoader classLoader, final JavaModule module) {
          return builder.visit(Advice.to(InstanceCounter.class).on(any()));
    .installOn(ByteBuddyAgent.install());
  @Advice.OnMethodEnter
  public static void enter(final @Advice.Origin Class<?> origin) {
    if (!BootstrapState.trace || BootstrapState.lock)
      return;
    BootstrapState.lock = true;
    System.out.println(">>> " + origin);
    BootstrapState.lock = false;
public class InstanceCounterTest {
  @Test
  public void test() {
    InstanceCounter.load();
    System.out.println("Creating array...");
    BootstrapState.trace = true;
    final Object[] y = new Object[3];
    BootstrapState.trace = false;