Memory overhead and performance loss of golang reflection

Reflection brings memory overhead and performance loss: Reflection stores type information in the reflect.Type structure, resulting in memory overhead. Reflection operations are slower than direct access to type information, increasing performance overhead. Practical examples demonstrate the memory overhead and performance differences of reflection.

GoLang Reflection Memory Overhead and Performance Loss

Reflection is a powerful tool that allows you to dynamically inspect and manipulate runtime type information. However, reflection also brings some memory overhead and performance losses.

Memory overhead

Reflection stores type information in a reflect.Type structure, which contains all necessary information about the type, such as fields, methods, and implementations Interface. Each reflect.Type structure requires additional memory overhead, which may become significant when dealing with large numbers of types.

Performance loss

Reflected operations are generally slower than direct access to type information. This is because reflection involves an extra layer of indirection, which incurs a performance overhead. For example, getting the field values ​​of a structure through reflection is slower than accessing the field values ​​directly.

Practical case

The following code example demonstrates the memory overhead and performance penalty of reflection:

package main

import (
    "reflect"
    "runtime"
    "testing"
)

type Example struct {
    Field1 string
    Field2 int
}

func BenchmarkReflectType(b *testing.B) {
    e := Example{}
    for i := 0; i < b.N; i++ {
        _ = reflect.TypeOf(e)
    }
}

func BenchmarkDirectType(b *testing.B) {
    e := Example{}
    for i := 0; i < b.N; i++ {
        _ = reflect.Type(e)
    }
}

Running this benchmark will show the use of reflect.TypeOf The performance difference between getting the reflected value of a type and getting the type directly.

Conclusion

Reflection is a useful tool, but it will bring some memory overhead and performance losses. When using reflection, be sure to weigh these overheads against the benefits.

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