@Override
    public synchronized Request poll(Task task) {
        try (Jedis jedis = pool.getResource()) {
            String url = getRequest(jedis, task);
            if (StringUtils.isBlank(url)) {
                return null;
            }
            return getExtrasInItem(jedis, url, task);
        }
    }
the redis scheduler with priority
@author sai
Created by sai on 16-5-27.
webmagic-extension/src/main/java/us/codecraft/webmagic/scheduler/RedisPriorityScheduler.java