Restart mysql without stopping service

When system upgrading mysql package, it will stop mysql service. Here is my way to "Hold" user.

Steps:

1. Check database connection for each request
2. Check database connection:
• sleep the process for 10 seconds
• display a custom 500 page.
3. The custom 500 page shows "loading..." and will reload the page automatically.

Make a 500 error page which shows "loading" and will reload page in 5 seconds.


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