退出手机浏览器，websocket会自动关闭，不是长持续吗

Question

之前，websocket会出现自己关闭的问题。
所以我nginx使用了:

location /wss {  # websocket配置
proxy_read_timeout  36000s;

好像没啥效果。

于是我在前端定时发送客户端请求：

 setInterval(() => {
     ws.send(JSON.stringify(params));
  }, 50000);
  

是奏效的。

但是 一旦手机浏览器切换别的应用，过50s以后再打开网页websocket就自动关闭了
百思不得其解，websocket或者http协议不都是keep-alive 长连接的吗

Answer 1

手机上的应用,包括浏览器退到后台,通常会被操作系统暂停. 似乎Android上的Chrome会打开websockets，但是当屏幕关闭时它会完全暂停计时器。这会导致设备在服务器端心跳超时时断开连接，并且由于心跳计时器未在客户端运行，它将继续重新连接并断开连接。类似保持连接的功能最好还是通过原生的服务实现更靠谱些.

这里有个后台表现列表供参考

Mobile devices can have different behaviour:

in background tabs
when display is turned off
This ticket is to track state of things

Timers at mobile devices

Browser	Background	Display off	Background WW	Display off WW
Android browser	OK	fail	OK	fail
Android FF	fail	fail	OK	OK
Android Chrome	OK	OK	OK	OK
iOS Chrome	OK	fail	OK	fail
iOS Safari	fail	fail	fail	fail

iOS Safari - sometimes timer in background can continue working 0-20 seconds
iOS Safari - foreground tab continue working 10-15 seconds after display turned off
Conclusion
Everything is bad on ios. The only solution is to reselect master.
On android things are acceptable, if you generate timer events from WebWorker
SharedWorker will not help:
not supported in browsers with timer problems
not much needed in browsers without timer problems

结论是 Chrome 还不错!

Answer 2

谢邀。
可以了解一下web离线解决方案ServiceWorker