go语言中goroute使用:=遇到的坑

先看下源代码,预想从1至N总取出所有能被a或b整除的正整数之和,为了利用go语言的并行优势,特使用goroute特性来实现,同时使用普通顺序计算进行效率比较分析

package chango

import (
"fmt"
"time"
)

func get_sum_of_divisible(num int64, divider int64, resultChan chan int64) {
var sum int64 = 0
var value int64
for value = 1; value < num; value++ {
if value%divider == 0 {
sum += value
}
}
resultChan <- sum
}
func Zhengchu_testing(limit int64, one int64, two int64) {
resultchan := make(chan int64, 3)
var three int64
three = one * two

t_start := time.Now()

go get_sum_of_divisible(limit, one, resultchan)
go get_sum_of_divisible(limit, two, resultchan)
go get_sum_of_divisible(limit, three, resultchan)

one_sum, two_sum, three_sum := <-resultchan, <-resultchan, <-resultchan

var sum int64
var value int64
sum = one_sum + two_sum - three_sum

fmt.Println(sum)
t_end := time.Now()
fmt.Println(one_sum, two_sum, three_sum)
fmt.Printf("testing times1:%v\n", t_end.Sub(t_start))

sum = 0
t_start = time.Now()

for value = 1; value < limit; value++ {
if value%one == 0 {
sum += value

}
if value%two == 0 {
sum += value
}
if value%three == 0 {
sum -= value
}
}
fmt.Println(sum)
t_end = time.Now()
fmt.Printf("testing times2:%v\n", t_end.Sub(t_start))
}
然后在main包中调用该chango包
package main

import "./chango"

func main(){

chango.Zhengchu_testing(10,3,5)
}

初看上去,chango包没有语法毛病,但是实际测试发现,显然通过顺序计算10以内能被3或5整除的所有正整数分别为3,5,6,9,他们之和应该为23,能被3整数的整数之和为3+6+9=15,能被5整除的正整数之和为5,能被3*15=15的正整数之和为0
而通过goroute计算10以内内能被3或5整除的所有正整数之和却不是23,而是-13或13,这又是为什么呢?
通过调试发现,问题就出现在“:=”语句中
  one_sum, two_sum, three_sum := <-resultchan, <-resultchan, <-resultchan
多次运行
通过分别打印能被3或5或3*5=15的正整数之和,他们的结果竟然是0,18,5或0,5,18,这个结果竟然不唯一





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转载自www.cnblogs.com/it-tsz/p/9096905.html
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