below is some simple code:

[SimpleFilter]
public class MyController : ControllerBase
{
   public MyController() {
      <---------- I put a debugger here
   }

   [Route("")]
   public string Get() {
      return DateTime.Now.ToLongTimeString();
   }
}

public class SimpleFilterAttribute : Attribute, IAsyncResourceFilter
{
   
   public SimpleFilterAttribute() {
      // <---------- I put a debugger here
   }

   public async Task OnResourceExecutionAsync(ResourceExecutingContext context, ResourceExecutionDelegate next) {
     ...
   }
}

So we know that when the appication is running, it will create a new controller instance to handle each request, so if I make 5 requests, then 5 MyController instance will be newed up, I can verify it by putting a debugger in MyController's constructor, every time the control goes to the debugger.

So I assume the same thing should happen to filter too, a new fiter instance will be created to handle every new request, but strange things happen as below:

1-When the application first starts, the SimpleFilter's constructor gets invoke twice, which means two instance of SimpleFilter newed up, so why application creates two instances of this fiter?

2-After the application is running, everytime I make a new request, no new SimpleFilter instance created, it looks like a single filter instance is used to handle all requests, is it true? If it is true, why we need a new controller instance for every request while only a single filter instance is needed for all requests?