final URI uri = new URI(url);
            final String host = uri.getHost();
            if (host == null) {
                return;
            }
            final AtomicLong lastTime = lastTimes.putIfAbsent(host, new AtomicLong(SystemUtil.currentTimeMillis()));
            if (lastTime == null) {
                return;
            }
            synchronized (lastTime) {
                while (true) {

        QueueHolder queueHolder = sessionCache.get(sessionId);
        if (queueHolder == null) {
            queueHolder = new QueueHolder();
            final QueueHolder prevQueueHolder = sessionCache.putIfAbsent(sessionId, queueHolder);
            return prevQueueHolder == null ? queueHolder : prevQueueHolder;
        }
        return queueHolder;
    }

    /**