Concat
Demo package for Ускорение конкатенации строк в Go своими руками article.
Overview
This package provides simple functions that return concatenation results.
Can work faster than Go + operator.
You should not use this package, really. It's just an example.
Benchmarks
BenchmarkConcat2Operator/short-8 20000000 84.4 ns/op
BenchmarkConcat2Operator/longer-8 10000000 158 ns/op
BenchmarkConcat2Builder/short-8 20000000 70.7 ns/op
BenchmarkConcat2Builder/longer-8 10000000 127 ns/op
BenchmarkConcat2/short-8 30000000 57.3 ns/op
BenchmarkConcat2/longer-8 20000000 106 ns/op
BenchmarkConcat3Operator/short-8 20000000 103 ns/op
BenchmarkConcat3Operator/longer-8 10000000 217 ns/op
BenchmarkConcat3Builder/short-8 20000000 89.9 ns/op
BenchmarkConcat3Builder/longer-8 5000000 249 ns/op
BenchmarkConcat3/short-8 20000000 85.0 ns/op
BenchmarkConcat3/longer-8 10000000 189 ns/op
Number one is unsafe concatenation, second is strings.Builder with preallocated
buffer and "obvious" concatenation is the slowest one... unless CL123256 is applied.
Using the benchstat, here is the difference between concat and +:
name old time/op new time/op delta
Concat2/short-8 84.4ns ± 2% 64.3ns ± 4% -23.85% (p=0.000 n=14+15)
Concat2/longer-8 138ns ± 1% 118ns ± 1% -14.83% (p=0.000 n=13+15)
Concat3/short-8 105ns ± 5% 82ns ± 5% -22.29% (p=0.000 n=15+14)
Concat3/longer-8 218ns ± 1% 192ns ± 1% -11.95% (p=0.000 n=15+15)
If compared with AMD64 asm version for concat2:
name old time/op new time/op delta
Concat2/short-8 84.4ns ± 0% 56.9ns ± 5% -32.54% (p=0.000 n=15+15)
Concat2/longer-8 138ns ± 1% 107ns ± 0% -22.51% (p=0.000 n=13+15)
As a bonus, asm version also makes empty strings concatenation optimization, just like runtime version of concat would.
Example
package main
import (
"fmt"
"github.com/Quasilyte/concat"
)
func main() {
v := "world!"
fmt.Println(concat.Strings("hello, ", v)) // => "hello, world!"
}