扇入、扇出 （判斷大值素數）

普通的pipeline stage代碼

package main

import (
	"math/rand"
	"time"
	"fmt"
)

func main() {

	rands := func() interface{} {return rand.Intn(500000000)}

	toInt := func(done <-chan interface{},
	value <-chan interface{}) <-chan int {
		randInt := make(chan int)
		go func() {
			defer close(randInt)
			for v := range value {
				select {
				case <-done:
					return
				case randInt <- v.(int):
				}
			}
		}()
		return randInt
	}

	repeatRand:= func(done <-chan interface{},
		fn func() interface{} ) <-chan interface{} {


		intData := make(chan interface{})
		go func() {
			defer close(intData)
			for  {
				select {
				case <-done:
					fmt.Println("111Goroutine 退出")
					return
				case intData<- fn():
				}
			}
		}()
		return intData
	}
	Take := func(done <-chan interface{},
		valueStream <-chan interface{},
		num int) <-chan interface{}{

		takeStream := make(chan interface{})
		go func() {
			defer fmt.Println("222Goroutine 退出")
			defer close(takeStream)
			for i := 0; i < num; i++ {
				select {
				case <-done:
					return
				case takeStream <-<-valueStream:
				}
			}
		}()
		return takeStream
	}

	panduan := func(n int) bool {
		for i:=2;i<n;i++ {
			if n % i == 0 {
				return false
			}
		}
		return true
	}

	primeFinder := func(done <-chan interface{},
	value <-chan int) <-chan interface{} {
		primesTREAM := make(chan interface{})
		go func() {

			for v := range value {
				if panduan(v) {
					select {
					case <-done:
						return
					case primesTREAM<- v:
					}
				}else {
					continue
				}
			}
		}()

		return primesTREAM
	}
	done := make(chan interface{})
	start := time.Now()
	randIntStream := toInt(done,repeatRand(done,rands))
	fmt.Println("Primes: ")
	for prime := range Take(done,primeFinder(done,randIntStream),10) {
	fmt.Println(prime)
	}
	close(done)
	fmt.Printf("Search took:%v ",time.Since(start))
}

扇入扇出代碼

package main

import (
	"math/rand"
	"time"
	"fmt"
	"runtime"
	"sync"
)

func main() {

	rands := func() interface{} {return rand.Intn(500000000)}

	toInt := func(done <-chan interface{},
	value <-chan interface{}) <-chan int {
		randInt := make(chan int)
		go func() {
			defer close(randInt)
			for v := range value {
				select {
				case <-done:
					return
				case randInt <- v.(int):
				}
			}
		}()
		return randInt
	}

	repeatRand:= func(done <-chan interface{},
		fn func() interface{} ) <-chan interface{} {


		intData := make(chan interface{})
		go func() {
			defer close(intData)
			for  {
				select {
				case <-done:
					fmt.Println("111Goroutine 退出")
					return
				case intData<- fn():
				}
			}
		}()
		return intData
	}
	Take := func(done <-chan interface{},
		valueStream <-chan interface{},
		num int) <-chan interface{}{

		takeStream := make(chan interface{})
		go func() {
			defer fmt.Println("222Goroutine 退出")
			defer close(takeStream)
			for i := 0; i < num; i++ {
				select {
				case <-done:
					return
				case takeStream <-<-valueStream:
				}
			}
		}()
		return takeStream
	}

	panduan := func(n int) bool {
		for i:=2;i<n;i++ {
			if n % i == 0 {
				return false
			}
		}
		return true
	}

	primeFinder := func(done <-chan interface{},
	value <-chan int) <-chan interface{} {
		primesTREAM := make(chan interface{})
		go func() {

			for v := range value {
				if panduan(v) {
					select {
					case <-done:
						return
					case primesTREAM<- v:
					}
				}else {
					continue
				}
			}
		}()

		return primesTREAM
	}

	fanIn := func(done <- chan interface{},
	channels ...<-chan interface{}) <-chan interface{} {
		var wg sync.WaitGroup

		multiPlexedStream := make(chan interface{})
		mutiplex := func(c <-chan interface{}) {
			defer wg.Done()
			for i:= range c {
				select {
				case <-done:
					return
				case multiPlexedStream<-i:
				}
			}
		}
		wg.Add(len(channels))
		for _,c := range channels {
			go mutiplex(c)
		}
		go func() {
			wg.Wait()
			close(multiPlexedStream)
		}()
		return multiPlexedStream
	}

	done := make(chan interface{})

	start := time.Now()
	randIntStream := toInt(done,repeatRand(done,rands))
	// fmt.Println("Primes: ")
	// for prime := range Take(done,primeFinder(done,randIntStream),10) {
	// 	fmt.Println(prime)
	// }
	numinders := runtime.NumCPU()
	fmt.Printf("Spanning up %d prime finders", numinders)

	finders := make([]<-chan interface{},numinders)
	fmt.Println("Primes: ")
	for i := 0; i < numinders; i++ {
		finders[i] = primeFinder(done,randIntStream)
	}

	for prime := range Take(done,fanIn(done,finders...),10){
		fmt.Printf("\t%v\n",prime)
	}

	close(done)
	fmt.Printf("Search took:%v ",time.Since(start))
}

性能對比
普通:
24s左右
扇入扇出
12s左右
性能提升了50%.