1.使用redis做缓存服务数据库（第5点持久化）
https://blog.csdn.net/qq_43398758/article/details/125412705
2.解决nginx下websocket的长连接问题
https://baijiahao.baidu.com/s?id=1714370851394804830&wfr=spider&for=pc
websocket 实现长连接原理:
https://www.cnblogs.com/xxflz/p/16771515.html
https://jingyan.baidu.com/article/5d6edee254b65cd9ebdeec7a.html
https://blog.csdn.net/weixin_50966947/article/details/127683746