private ClassLoaderAttachment getClassLoaderAttachment(ClassLoader classLoader) {

        final ClassLoaderAttachment exist = classLoaderAttachment.get(classLoader);
        if (exist != null) {
            return exist;
        }
        final ClassLoaderAttachment newInfo = new ClassLoaderAttachment();
        final ClassLoaderAttachment old = classLoaderAttachment.putIfAbsent(classLoader, newInfo);
        if (old != null) {
            return old;
        }
        return newInfo;
    }
@author Woonduk Kang(emeroad)
@author jaehong.kim
agent-module/profiler/src/main/java/com/navercorp/pinpoint/profiler/instrument/classloading/PlainClassLoaderHandler.java