Tag
Concurrent execution: goroutines, channels, locks and taming race conditions.
3 answered questions carry this tag.
Move to `errgroup.WithContext` with a request-level timeout on top and thread ctx into every HTTP and DB call; an ignored ctx means no cancellation at all.
Cancellation propagates only if you pass `r.Context()` into every downstream call, leave no `context.Background()` in the chain, and use `WithoutCancel`.
Export NumGoroutine() as a metric, take a pprof goroutine dump at peak, make the spawn site behind the parked stacks honor ctx.Done(), then add goleak.