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

Empty Interface vs. Empty Struct in Go Maps

When creating a set-like structure in Go, it's common practice to utilize a map with an empty interface as its value. However, an alternate option is to use an empty struct as the value instead.

Memory Usage Benefits

The primary benefit of using an empty struct lies in its memory usage optimization. Consider the following:

package main

import "unsafe"

func main() {
    var emptyInterface interface{}
    var emptyStruct struct{}

    fmt.Println("Empty Interface Memory Usage:", unsafe.Sizeof(emptyInterface))
    fmt.Println("Empty Struct Memory Usage:", unsafe.Sizeof(emptyStruct))
}

The output demonstrates that the empty struct consumes less memory than the empty interface:

• 32-bit Architecture: 8 bytes for empty interface, 0 bytes for empty struct
• 64-bit Architecture: 16 bytes for empty interface, 0 bytes for empty struct

Other Considerations

While memory usage is a critical factor, it's important to note other considerations when choosing between an empty interface and an empty struct:

• Code readability: An empty struct may improve readability as it explicitly indicates that the value is empty.
• Flexibility: An empty interface provides greater flexibility as it can hold values of any type. An empty struct has a fixed type.

Conclusion

The decision between using an empty interface and an empty struct as the value in a Go map depends on specific requirements. If memory efficiency is a priority, an empty struct is a viable option. However, if the need for flexibility outweighs memory considerations, an empty interface might be a more appropriate choice.

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