Go Concurrency Patterns (Deep Dive)

Structured concurrency

• Every goroutine has an owner
• errgroup + context
• No fire‑and‑forget

Cancellation

• Check ctx.Done in loops
• select on send/recv

Backpressure

• Bounded queues
• Semaphores
• Load shedding

Worker pools

• Fixed workers
• Producer closes jobs
• Aggregator closes results

Fan‑out / Fan‑in

• Single writer aggregation
• Explicit ordering

Safe publication

• Channels / mutex / atomic.Value
• Happens‑before

Contention control

• Shard state
• Batch updates
• Immutable + swap

Timers

• Avoid time.After in loops
• Reuse timers

sync.Pool

• Not a cache
• Short‑lived buffers only

Testing

• -race
• stress + cancellation checks