Diagnostics with Tracing, a Unified Instrumentation System for Rust

Hi! I'm the author of the post & the primary maintainer of `tracing`— happy to answer any questions!

Does this use a thread local approach, or a Go-style ctx parameter? Since it's async I expected to see the ctx approach, unless the underlying async executor/framework also supports a thread local-ish capability?

I wonder how much can be infered from runtime execution to create useful traces..