Is There a Performance Difference Between `make` and `{}` for Map Initialization in Go?

Performance Comparison of Map Initialization Methods in Go: make vs. {}

In Go, maps can be initialized using two primary methods:

<code class="go">var myMap map[string]int
myMap = map[string]int{}</code>

vs.

<code class="go">myMap = make(map[string]int)</code>

The question arises whether there is any noticeable performance difference between these approaches.

Performance Evaluation

To assess the performance, a benchmark test was conducted using a custom testing package. The results across multiple runs indicated negligible differences between the two methods. The following is a sample benchmark code:

<code class="go">package bench

import "testing"

var result map[string]int

func BenchmarkMakeLiteral(b *testing.B) {
    var m map[string]int
    for n := 0; n < b.N; n++ {
        m = InitMapLiteral()
    }
    result = m
}

func BenchmarkMakeMake(b *testing.B) {
    var m map[string]int
    for n := 0; n < b.N; n++ {
        m = InitMapMake()
    }
    result = m
}

func InitMapLiteral() map[string]int {
    return map[string]int{}
}

func InitMapMake() map[string]int {
    return make(map[string]int)
}</code>

Benchmark Results

The benchmark results for three separate runs were as follows:

$ go test -bench=.
testing: warning: no tests to run
PASS
BenchmarkMakeLiteral-8  10000000               160 ns/op
BenchmarkMakeMake-8     10000000               171 ns/op
ok      github.com/johnweldon/bench     3.664s

$ go test -bench=.
testing: warning: no tests to run
PASS
BenchmarkMakeLiteral-8  10000000               182 ns/op
BenchmarkMakeMake-8     10000000               173 ns/op
ok      github.com/johnweldon/bench     3.945s

$ go test -bench=.
testing: warning: no tests to run
PASS
BenchmarkMakeLiteral-8  10000000               170 ns/op
BenchmarkMakeMake-8     10000000               170 ns/op
ok      github.com/johnweldon/bench     3.751s

Conclusion

Based on these benchmark results, there is no significant performance difference between initializing maps using map[string]int{} and make(map[string]int). Both methods exhibit nearly identical performance on a sample machine.

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