闭包、匿名函数和普通函数的基准

除此之外,一些代码生成和一些优化比其他更容易完成。有关详细信息,请参阅go gc编译器源代码。

$ go version
go version devel +e68ac45172 Fri Jul 20 16:04:01 2018 +0000 linux/amd64

未优化:

$ go test bench_test.go -bench=. -benchmem -gcflags='-N'
goos: linux
goarch: amd64
BenchmarkClosure-4         1    2621664326 ns/op    0 B/op    0 allocs/op
BenchmarkAnonymous-4       1    1995507678 ns/op    0 B/op    0 allocs/op
BenchmarkFunction-4        1    2297303813 ns/op    0 B/op    0 allocs/op

优化:

$ go test bench_test.go -bench=. -benchmem
goos: linux
goarch: amd64
BenchmarkClosure-4         2     585091582 ns/op    0 B/op    0 allocs/op
BenchmarkAnonymous-4       5     287299925 ns/op    0 B/op    0 allocs/op
BenchmarkFunction-4        5     287710165 ns/op    0 B/op    0 allocs/op

bench_test.go :

package main

import "testing"

func X(p *int) {
    *p += 1
}

var N = 1000000000

func BenchmarkClosure(b *testing.B) {
    for n := 0; n < b.N; n++ {
        for i := 0; i < N; i++ {
            p := 0
            x := func() {
                p += 1
            }
            x()
        }
    }
}

func BenchmarkAnonymous(b *testing.B) {
    for n := 0; n < b.N; n++ {
        for i := 0; i < N; i++ {
            p := 0
            func() {
                p += 1
            }()
        }
    }
}

func BenchmarkFunction(b *testing.B) {
    for n := 0; n < b.N; n++ {
        for i := 0; i < N; i++ {
            p := 0
            X(&p)
        }
    }
}