I am studying about golang and use of goroutine.
With this sample code, on my PC with 4 logical CPUs, I can't understand why I don't have any performance improvement.
If I add in concurrency, the time it takes to do tends to slow down by the original without concurrency.
2017/10/27 13:57:17 Starting 1 threads
2017/10/27 13:57:27 Id routine: 0 rate: 232.558140
2017/10/27 13:57:27 Current total rate was 232.56 K/s
2017/10/27 13:57:27 Starting 1 threads
2017/10/27 13:57:37 Id routine: 0 rate: 357.142857
2017/10/27 13:57:37 Current total rate was 357.14 K/s
2017/10/27 13:58:04 Starting 2 threads
2017/10/27 13:58:14 Id routine: 0 rate: 131.578947
2017/10/27 13:58:14 Id routine: 1 rate: 129.870130
2017/10/27 13:58:14 Current total rate was 261.45 K/s
2017/10/27 13:58:14 Starting 2 threads
2017/10/27 13:58:24 Id routine: 1 rate: 144.927536
2017/10/27 13:58:24 Id routine: 0 rate: 151.515152
2017/10/27 13:58:24 Current total rate was 296.44 K/s
2017/10/27 13:59:15 Starting 3 threads
2017/10/27 13:59:25 Id routine: 2 rate: 94.339623
2017/10/27 13:59:25 Id routine: 0 rate: 92.592593
2017/10/27 13:59:25 Id routine: 1 rate: 90.090090
2017/10/27 13:59:25 Current total rate was 277.02 K/s
2017/10/27 13:59:25 Starting 3 threads
2017/10/27 13:59:35 Id routine: 2 rate: 92.592593
2017/10/27 13:59:35 Id routine: 0 rate: 90.090090
2017/10/27 13:59:35 Id routine: 1 rate: 101.010101
2017/10/27 13:59:35 Current total rate was 283.69 K/s
2017/10/27 14:00:12 Starting 4 threads
2017/10/27 14:00:22 Id routine: 1 rate: 56.818182
2017/10/27 14:00:22 Id routine: 3 rate: 56.818182
2017/10/27 14:00:22 Id routine: 0 rate: 61.349693
2017/10/27 14:00:22 Id routine: 2 rate: 62.500000
2017/10/27 14:00:22 Current total rate was 237.49 K/s
2017/10/27 14:00:22 Starting 4 threads
2017/10/27 14:00:32 Id routine: 1 rate: 67.114094
2017/10/27 14:00:32 Id routine: 3 rate: 61.349693
2017/10/27 14:00:32 Id routine: 0 rate: 57.803468
2017/10/27 14:00:32 Id routine: 2 rate: 65.789474
2017/10/27 14:00:32 Current total rate was 252.06 K/s
And, here is the concurrent code with the goroutines:
package main
import (
"fmt"
"log"
"sync"
"time"
)
var (
tryArr []string
goroutineQuit = make(chan struct{})
concurrencyMapHQ = struct {
sync.RWMutex
HQ map[int]float64
}{HQ: make(map[int]float64)}
)
func rateStats() {
var totalRate float64
for i, rate := range concurrencyMapHQ.HQ {
log.Printf("Id routine: %d rate: %f", i, rate)
totalRate += rate
}
log.Printf("Current total rate was %.2f K/s", totalRate)
}
func stopThreads(threads int) {
for i := 0; i < threads; i++ {
goroutineQuit <- struct{}{}
}
rateStats()
}
func runThreads(threads int, steps int) {
log.Printf("Starting %d threads", threads)
for i := 0; i < threads; i++ {
i := i
go func(id int, steps int) {
calculate(i, steps)
}(i, steps)
}
}
func calculate(idRoutine int, steps int) {
var (
possibles []string
numBatchs = 0
t1 = time.Now()
)
for {
select {
case <-goroutineQuit:
return
default:
possibles = nil
for _, nonce := range tryArr {
possibles = append(possibles, nonce)
}
numBatchs++
if numBatchs == 99 {
t2 := time.Now()
timeExecution := t2.Sub(t1) / time.Millisecond
concurrencyMapHQ.Lock()
concurrencyMapHQ.HQ[idRoutine] = float64(steps) / float64(timeExecution)
concurrencyMapHQ.Unlock()
numBatchs = 0
t1 = t2
}
}
}
}
func main() {
threads := 4
steps := 10000
tryArr = make([]string, steps)
for i := 0; i < steps; i++ {
tryArr[i] = fmt.Sprintf("indice: %d", i)
}
for {
runThreads(threads, steps)
time.Sleep(10 * time.Second)
stopThreads(threads)
runThreads(threads, steps)
time.Sleep(10 * time.Second)
stopThreads(threads)
}
}
