EventEmitter {
domain: null,
_events: {},
_eventsCount: 0,
_maxListeners: undefined,
Worker://有一个worker对象
{ [Function: Worker]
super_:
{ [Function: EventEmitter]
EventEmitter: [Circular],
usingDomains: false,
defaultMaxListeners: 10,
init: [Function],
listenerCount: [Function]
}