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go.cpu_in_hot_path

Performance Medium

Detects CPU-intensive operations (reflection, regex, JSON marshaling) in frequently-called code paths.

Why It Matters

CPU work in hot paths causes:

Increased latency — P99 latency spikes
Reduced throughput — Less requests per second
Higher costs — Need more instances to handle load
Poor scaling — Performance degrades under load

Example

// ❌ Before (expensive in loop)
func processItems(items []Item) {
    for _, item := range items {
        json.Marshal(item) // Reflection on every iteration
        reflect.TypeOf(item) // Even more expensive
    }
}

// ✅ After (optimized)
func processItems(items []Item) {
    // Batch marshal if needed
    data, _ := json.Marshal(items)

    // Or pre-compute type information
    itemType := reflect.TypeOf(Item{})
    for _, item := range items {
        // Use cached type info
    }
}

What Unfault Detects

reflect package usage in loops
JSON marshal/unmarshal in hot paths
Regex operations in loops (use pre-compiled patterns)
Hash computations in tight loops

Auto-Fix

Unfault suggests moving expensive operations out of loops or pre-computing values.