Empty Struct vs. Empty Interface in Go Maps: Which is More Memory Efficient?

Memory Efficiency Considerations: Empty Interface vs. Empty Struct in Maps

One may wonder about the distinction between using an empty interface and an empty struct as the value in a map when seeking to emulate a set in Go. Let's delve into the memory usage differences that arise from this choice.

Consider the following types:

type MyType uint8

To simulate a set, one might utilize the following construct:

map[MyType]interface{}

However, it's worth noting that one can also employ an empty struct instead:

map[MyType]struct{}

The primary benefit of using an empty struct is its reduced memory usage compared to an empty interface. The following example demonstrates this difference:

package main

import (
    "fmt"
    "unsafe"
)

func main() {
    var s struct{}
    fmt.Println(unsafe.Sizeof(s))
    var i interface{}
    fmt.Println(unsafe.Sizeof(i))
}

Output (bytes for 32-bit architecture):

0
8

Output (bytes for 64-bit architecture):

0
16

As the results indicate, an empty struct occupies zero bytes of memory, while an empty interface consumes either 8 or 16 bytes depending on the architecture.

Therefore, if memory efficiency is a crucial consideration, opting for an empty struct as the value in your map is a wise choice.

The above is the detailed content of Empty Struct vs. Empty Interface in Go Maps: Which is More Memory Efficient?. For more information, please follow other related articles on the PHP Chinese website!