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go.reflect_in_hot_path

Performance Medium

Detects reflect package usage in frequently-called code paths.

Why It Matters

Reflection in hot paths:

10-100x slower — Reflection bypasses compile-time optimizations
More allocations — Reflect creates temporary objects
No inlining — Defeats compiler optimizations

Example

// ❌ Before (reflection in loop)
func processItems(items []interface{}) {
    for _, item := range items {
        v := reflect.ValueOf(item)
        // Reflection on every iteration
    }
}

// ✅ After (type assertion)
func processItems(items []Item) {
    for _, item := range items {
        // Direct field access, no reflection
        process(item.Name)
    }
}

What Unfault Detects

reflect.ValueOf() in loops
reflect.TypeOf() in handlers
Reflection in hot code paths

Auto-Fix

Unfault suggests type assertions or interfaces:

// Use type switch instead of reflection
switch v := item.(type) {
case string:
    processString(v)
case int:
    processInt(v)
}