What is a livelock and how does it differ from a deadlock in Go programs?

A deadlock: all goroutines are blocked — no progress is possible. A livelock: all goroutines are actively running but constantly reacting to each other in a loop that prevents any meaningful progress — like two people in a corridor who keep stepping in the same direction to let the other pass.

// DEADLOCK: goroutines blocked — Go runtime detects it
ch := make(chan int)
ch <- 1  // send blocks, no receiver → runtime: 'all goroutines asleep'

// LIVELOCK: goroutines running but making no net progress
type lock struct{ taken bool }

func acquirePolite(own, other *lock) {
    for {
        own.taken = true
        time.Sleep(time.Millisecond)
        if other.taken {     // the other goroutine also has its lock
            own.taken = false // politely give up and retry → infinite loop!
            time.Sleep(time.Millisecond)
            continue
        }
        other.taken = true
        break // rarely reached
    }
}

a, b := &lock{}, &lock{}
go acquirePolite(a, b) // both goroutines busy but stuck
go acquirePolite(b, a)

// Go runtime does NOT detect livelocks — goroutines are 'running'

// Detection:
// - CPU at 100% with no observable progress
// - pprof CPU profile shows same functions in an infinite spin
// - go tool trace shows goroutines executing but state never advancing

// Prevention:
// - Randomised exponential backoff: rand.Sleep between retries
// - Consistent lock-acquisition ordering
// - Prefer context-based timeouts over spin-wait patterns

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