ASP.NET Core 2 MVC中，IWebHost.Start()方法的适用场景有哪些？

Great question! Let's break down the practical scenarios where IWebHost.Start() is the right pick, especially since it doesn't block the calling thread (unlike Run(), which holds the thread hostage until the host shuts down).

• Integration Testing Workflows
  This is one of the most common use cases. When writing integration tests (with frameworks like xUnit or NUnit), you need to spin up a web server, send test requests to it, then tear it down cleanly. Start() lets you launch the host without blocking your test thread—you can immediately use an HttpClient to validate API responses, then explicitly stop the host once tests finish. No messy background thread hacks required.

• Hosting Multiple Web Services in One Process
  If your app needs to run multiple distinct web hosts (like separate APIs on different ports, or with unique configurations) within a single process, Start() is essential. You can start each IWebHost instance sequentially without getting stuck on a blocked thread, then manage their lifecycles independently. For example, you could listen for a shutdown signal and gracefully stop all hosts when needed, instead of being tied to one blocked thread.

• Console Apps with Dual Responsibilities
  Imagine a console app that needs to run both a web API and handle background tasks—like processing message queues, running scheduled jobs, or monitoring system resources. Start() fires up the web host and returns control to the main thread right away, so you can run your background logic alongside the web service. With Run(), your background code would never execute because the thread would be locked up by the web host.

• Custom Lifecycle Control
  When you need full control over when the web host starts and stops, Start() is your go-to. Maybe your app waits for an external resource (like a database connection or configuration signal) before launching the web service, or needs to shut down the host in response to an internal event (not just a console interrupt). Since Start() doesn't block, you can handle these lifecycle triggers in your main thread logic without being tied to the web host's blocking loop.

Just a quick reminder: since Start() doesn't block, you need to make sure your app doesn't exit right after calling it. You'll usually add a way to wait for a shutdown signal (like listening for Ctrl+C) or manage the host's lifecycle explicitly to keep the process running.

内容的提问来源于stack exchange，提问作者Andrey Bushman