[ Golang ] Go 루틴 최대갯수를 제한하기

DB 배치 작업을 하거나 외부 API 를 사용할때 커넥션 갯수가 너무 많아지는것이 부담스러울때 고루틴을 다음과 같이 제한 가능하다.

 

package example_limit_gorutine

import (
	"fmt"
	"log"
	"sync"
	"time"
)

func SelectTable(offset int) {
	time.Sleep(300 * time.Millisecond)
	log.Println(fmt.Sprintf("select * from table limit %d,10", offset))
}

func Run(concurrentCount int, totalCount int) {
	concurrentGoroutines := make(chan struct{}, concurrentCount)
	var wg sync.WaitGroup
	for offset := 0; offset < totalCount; offset += 10 {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			concurrentGoroutines <- struct{}{}
			SelectTable(i)
			<-concurrentGoroutines

		}(offset)

	}
	wg.Wait()
}




package example_limit_gorutine_test

import (
	"github.com/hoyeonUM/golang-example/example_limit_gorutine"
	"github.com/stretchr/testify/assert"
	"testing"
	"time"
)

func TestConcurrent(t *testing.T) {
	t.Run("given concurrent count 10 and total count 100 when increase number 10 and wait time is 300ms then over execute time ge 1500ms", func(t *testing.T) {
		startTime := time.Now()
		example_limit_gorutine.Run(2, 100)
		endTime := time.Now()
		assert.GreaterOrEqual(t, endTime.Sub(startTime).Milliseconds(), int64(1500))
	})
}

 

참고자료

gist.github.com/AntoineAugusti/80e99edfe205baf7a094