python - When does the App Engine scheduler use a new thread vs. a new instance?

Question

If I set threadsafe: true in my app.yaml file, what are the rules that govern when a new instance will be created to serve a request, versus when a new thread will be created on an existing instance?

If I have an app which performs something computationally intensive on each request, does multi-threading buy me anything? In other words, is an instance a multi-core instance or a single core?

Or, are new threads only spun up when existing threads are waiting on IO?

Answer 1

Waitting for answers