Find channel IO overhead

channel_test.go

/* Benchmarks summing serially and then with channels
 * to time how much overhead channel reads have.
 * To run: `go test -bench . channel_test.go`
 */
package channel_test

import (
    "sync"
    "testing"
)

func BenchmarkSerial(b *testing.B) {
    var sum int
    for i := 0; i < b.N; i++ {
        sum += i
    }
}


func BenchmarkChanBuffered(b *testing.B) {
    ch := make(chan int, b.N)
    channelTest(b, ch)
}

func BenchmarkChanUnbuffered(b *testing.B) {
    ch := make(chan int)
    channelTest(b, ch)
}

func channelTest(b *testing.B, ch chan int) {
    var wg sync.WaitGroup
    done := make(chan bool)
    wg.Add(2)
    go channelOut(b.N, ch, done, &wg)
    go channelIn(ch, done, &wg)
    wg.Wait()
}

func channelOut(n int, ch chan<- int, done chan bool, wg *sync.WaitGroup) {
    defer wg.Done()
    for i := 0; i < n; i++ {
        ch <- i
    }
    done <- true
}

func channelIn(ch <-chan int, done chan bool, wg *sync.WaitGroup) {
    defer wg.Done()
    var sum int
    for {
        select {
        case num := <-ch:
            sum += num
        case <-done:
            return
        }
    }
}

My test results on a 2015 Macbook Pro:

goos: darwin
goarch: amd64
BenchmarkSerial-8 2000000000 0.32 ns/op
BenchmarkChanBuffered-8 30000000 50.9 ns/op
BenchmarkChanUnbuffered-8 3000000 422 ns/op
PASS
ok command-line-arguments 3.998s