环境：linux redhat 2.6.18-194.el5
JDK: 1.6.0_27 x64
btrace版本: 1.2.3
tomcat:7.0.22

场景:
把btrace-agent加载到tomcat中启动, 并且只加载一个Btrace脚本文件，启动时出现死锁，而且是每次必现。

Thread dump如下:

Found one Java-level deadlock:
=============================
"pool-1-thread-1":
  waiting to lock monitor 0x000000005fcf5680 (object 0x00000007590e6b48, a sun.misc.Launcher$AppClassLoader),
  which is held by "main"
"main":
  waiting to lock monitor 0x000000005fcf4180 (object 0x000000060644f890, a <unknown>),
  which is held by "pool-1-thread-1"


Java stack information for the threads listed above:
===================================================
"pool-1-thread-1":
        at com.sun.btrace.runtime.ClassFilter.isCandidate(ClassFilter.java:158)
        at com.sun.btrace.runtime.ClassFilter.isCandidate(ClassFilter.java:145)
        at com.sun.btrace.agent.Client.transform(Client.java:160)
        at sun.instrument.TransformerManager.transform(TransformerManager.java:169)
        at sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:365)
        at java.util.HashMap.entrySet0(HashMap.java:945)
        at java.util.HashMap.entrySet(HashMap.java:940)
        at java.lang.Class.initAnnotationsIfNecessary(Class.java:3078)
        - locked <0x000000060635c900> (a java.lang.Class for java.util.concurrent.ThreadPoolExecutor)
        at java.lang.Class.getAnnotation(Class.java:3029)
        at com.sun.btrace.runtime.ClassFilter.isCandidate(ClassFilter.java:95)
        at com.sun.btrace.agent.Client.isCandidate(Client.java:321)
        at com.sun.btrace.agent.Main$4.run(Main.java:417)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:662)
"main":
        at com.sun.btrace.runtime.ClassFilter.isCandidate(ClassFilter.java:158)
        at com.sun.btrace.runtime.ClassFilter.isCandidate(ClassFilter.java:145)
        at com.sun.btrace.agent.Client.transform(Client.java:160)
        at sun.instrument.TransformerManager.transform(TransformerManager.java:169)
        at sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:365)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        - locked <0x00000007590e6b48> (a sun.misc.Launcher$AppClassLoader)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        - locked <0x00000007590e6b48> (a sun.misc.Launcher$AppClassLoader)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:247)


Found 1 deadlock.

问题：可以看到thread-1对某个对象加了锁，但是这个对象显示的是<unknown>, 请问如何确定这个是什么锁？

PS：发现出现问题的代码行是创建了一个对象，该对象中有一个行代码创建了一个匿名类，并对其进行了实例化，如果将匿名类改成普通类，则死锁消失，不知道JVM在处理匿名类初始化的时候是否有特殊处理？

    private class CheckingVisitor extends ClassVisitor {

        private boolean isInterface;
        private boolean isCandidate;
        private AnnotationVisitor nullAnnotationVisitor = new AnnotationVisitor(Opcodes.ASM4) {};