Production patterns for async Rust with Tokio, channels, error handling, and concurrent task management.

• Covers seven core patterns: concurrent task execution with JoinSet and select!, multi-producer channels (mpsc, broadcast, oneshot, watch), custom error types with anyhow and thiserror, graceful shutdown via CancellationToken, async traits with async_trait, streams and async iteration, and resource pooling with RwLock and Semaphore
• Includes practical examples for racing futures, limiting concurrency, timeout handling, and task cancellation across shutdown scenarios
• Provides debugging guidance using tokio-console, tracing instrumentation, and common pitfalls like blocking in async contexts or holding locks across awaits
• Best practices section covers when to use channels over shared state, proper error propagation, and spawn limits to prevent resource exhaustion