Performance

Allocation Reduction (Uber style)

• Pre-allocate slices: make([]T, 0, expectedCap)
• Pre-allocate maps: make(map[K]V, expectedSize)
• Use sync.Pool for frequently allocated/deallocated objects
• Prefer strconv over fmt for primitive conversions (significantly faster)
• Use strings.Builder for string concatenation in loops
• Avoid fmt.Sprintf in hot paths
• Avoid interface boxing in hot paths (causes heap allocation)
• Use pointer receivers to avoid copying large structs
• Check escape analysis: go build -gcflags='-m'
• Avoid repeated string-to-byte conversions — cache the result

Concurrency Performance

• Use sync.Map only for read-heavy workloads with stable keys
• Prefer sharded maps with sync.RWMutex for write-heavy workloads
• Bound goroutine creation with worker pools or semaphores
• Use runtime.GOMAXPROCS() awareness for CPU-bound work
• Channels should have size zero or one — profile before using larger buffers
• Use go.uber.org/goleak in tests to detect goroutine leaks

HTTP / Network

• Reuse http.Client and http.Transport — never create per-request
• Set MaxIdleConns, MaxIdleConnsPerHost, IdleConnTimeout
• Use context.WithTimeout for all outbound calls
• Enable HTTP/2 where supported
• Use connection pooling for database clients

Kubernetes Controller Performance

• Use informer caches — never list from the API server in reconcile
• Use predicates to filter events before they reach the reconciler
• Set appropriate MaxConcurrentReconciles for the workload
• Use client.Reader (cached) for reads, client.Writer for writes
• Avoid unnecessary status updates — compare before writing

Continuous Profiling (Production)

• Use Grafana Pyroscope for continuous profiling in production
• Push mode: github.com/grafana/pyroscope-go SDK
• Pull mode: Grafana Alloy scraping pprof endpoints
• See PERF.md for Docker Compose and Kubernetes deployment
• Record findings in beads: bd create "Perf: finding" --type note --labels perf

Recording Results

After profiling, record findings in beads for persistent memory:

bd create "Perf: description of finding" --type note --labels perf,context
bd create "Baseline: metric at N resources" --type note --labels perf,baseline