[Bug] The log info about eventQueue.size() may be inaccurate in NettyEventExecutor

[horizonzy]

BUG REPORT

1. Please describe the issue you observed:
   I notice the code in NettyEventExecutor as follow:

    class NettyEventExecutor extends ServiceThread {
        private final LinkedBlockingQueue<NettyEvent> eventQueue = new LinkedBlockingQueue<NettyEvent>();
        private final int maxSize = 10000;

        public void putNettyEvent(final NettyEvent event) {
            if (this.eventQueue.size() <= maxSize) {
                this.eventQueue.add(event);
            } else {
                log.warn("event queue size[{}] enough, so drop this event {}", this.eventQueue.size(), event.toString());
            }
        }
     ......
    }

When the eventQueue.size() more than 10000, the event will be discard, then log info.
Because the putNettyEvent is not sync, so the eventQueue can more than 10000, when putEvent to queue, the size more than 10000. And when log info, the size may less than 10000.

It should use one variable value to log it.