#Mutex

Three deadlocks in production, all with the same face: the service stopped responding — no error, no panic, no log. What I found while diagnosing them changed how I think about lock design in async Rust.

Three Go counters under contention. atomic wins for one hot counter. mutex is fine for batched updates. sync.Map almost never earns its keep.

A buffered channel op is several times more expensive than a mutex. The gap shows up at scale. When to pick which, with benchmarks.

You're staring at your assignment, half your IDE windows open, and the clock keeps ticking. The...