Give an example when componentWillMount can be called multiple times

I've found such phrase on this page https://reactjs.org/blog/2018/03/27/update-on-async-rendering.html about componentWillMount callback:

The above code is problematic for both server rendering (where the external data won’t be used) and the upcoming async rendering mode (where the request might be initiated multiple times).

The same problem is described for componentWillUpdate and componentWillReceiveProps.

If I'm not mistaken it means that this function can be executed multiple times for one component if I use async rendering. I've found such question on StackOverflow: https://stackoverflow.com/questions/54533907/react-componentwillupdate-getting-called-twice about the same problem. I think I understand theoretical possibility of case when componentWillMount will be called twice: it can happen when mouning and initial rendering of some component was interrupted with higher priority task, so mounting restarts and calls componentWillMount again. Unfortunately neither documentation nor StackOverflow has any practical example of code which cause multiple calls of componentWillMount.

I've tried to make such an example myself using experimental React.JS version but has no luck.

I think it's better to have such an example to allow people who is not an expert in React.JS source code to under problem of such lifetime callbacks usage. I understand that it's an experimental feature and it can be changed in future but it's easier to understand the conception of async rendering when you have practical examples of possible problems.

首先阅读链接的 React 博客文章和所引用的 Stack Overflow 问题，然后查看相关文档页面中关于 async-rendering 生命周期的指导。文档包含一个实际示例，展示 componentWillMount 如何被多次调用，并清楚说明由此产生的使用问题后，工作即完成。