Looking at `NettyApplicationEngine`, why does ktor...

# ktor

[rrva]

Looking at NettyApplicationEngine, why does ktor run application code in a threadpool of its own?

[cy]

This is required to safely run any code that can potentially block

[rrva]

oh, so this is the only reason, nothing with scaling the i/o threads vs user threads? does the context switch to a new set of threads cost much?