ZkServer服务启动的逻辑-NIOServerCnxnFactory.start

这里通过thread.start启动一个线程，那thread是一个什么对象呢？

public void start() { 
	// ensure thread is started once and only once 
	if (thread.getState() == Thread.State.NEW) { 
		thread.start(); 
	} 
}