// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build ignore
package main
import (
"fmt"
"code.google.com/p/go-tour/tree"
)
func walkImpl(t *tree.Tree, ch chan int) {
if t == nil {
return
}
walkImpl(t.Left, ch)
ch <- t.Value
walkImpl(t.Right, ch)
}
// Walk walks the tree t sending all values
// from the tree to the channel ch.
func Walk(t *tree.Tree, ch chan int) {
walkImpl(t, ch)
// Need to close the channel here
close(ch)
}
// Same determines whether the trees
// t1 and t2 contain the same values.
// NOTE: The implementation leaks goroutines when trees are different.
// See binarytrees_quit.go for a better solution.
func Same(t1, t2 *tree.Tree) bool {
w1, w2 := make(chan int), make(chan int)
go Walk(t1, w1)
go Walk(t2, w2)
for {
v1, ok1 := <-w1
v2, ok2 := <-w2
if !ok1 || !ok2 {
return ok1 == ok2
}
if v1 != v2 {
return false
}
}
}
func main() {
fmt.Print("tree.New(1) == tree.New(1): ")
if Same(tree.New(1), tree.New(1)) {
fmt.Println("PASSED")
} else {
fmt.Println("FAILED")
}
fmt.Print("tree.New(1) != tree.New(2): ")
if !Same(tree.New(1), tree.New(2)) {
fmt.Println("PASSED")
} else {
fmt.Println("FAILED")
}
}
在此代码中,http://tour.golang.org/concurrency/8
的解决方案为什么有关于Same()函数的注释相同(t1,t2 * tree.Tree)bool说它泄漏了goroutines?怎么会这样?它还提到了第二个修复此问题的文件:
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build ignore
package main
import (
"fmt"
"code.google.com/p/go-tour/tree"
)
func walkImpl(t *tree.Tree, ch, quit chan int) {
if t == nil {
return
}
walkImpl(t.Left, ch, quit)
select {
case ch <- t.Value:
// Value successfully sent.
case <-quit:
return
}
walkImpl(t.Right, ch, quit)
}
// Walk walks the tree t sending all values
// from the tree to the channel ch.
func Walk(t *tree.Tree, ch, quit chan int) {
walkImpl(t, ch, quit)
close(ch)
}
// Same determines whether the trees
// t1 and t2 contain the same values.
func Same(t1, t2 *tree.Tree) bool {
w1, w2 := make(chan int), make(chan int)
quit := make(chan int)
defer close(quit)
go Walk(t1, w1, quit)
go Walk(t2, w2, quit)
for {
v1, ok1 := <-w1
v2, ok2 := <-w2
if !ok1 || !ok2 {
return ok1 == ok2
}
if v1 != v2 {
return false
}
}
}
func main() {
fmt.Print("tree.New(1) == tree.New(1): ")
if Same(tree.New(1), tree.New(1)) {
fmt.Println("PASSED")
} else {
fmt.Println("FAILED")
}
fmt.Print("tree.New(1) != tree.New(2): ")
if !Same(tree.New(1), tree.New(2)) {
fmt.Println("PASSED")
} else {
fmt.Println("FAILED")
}
}
它是如何实现的?泄漏在哪里? (要测试代码,您必须在http://tour.golang.org/concurrency/8上运行它)。非常困惑,并希望得到一些帮助,谢谢!
答案 0 :(得分:2)
当检测到差异时,程序停止在频道上接收。
walk goroutines一直运行,直到阻止发送到频道。他们永远不会退出这是泄漏。
答案 1 :(得分:0)
第二个解决方案使用退出通道处理泄漏。当退出通道关闭时(在Same()函数中),select语句的情况2成功(在walkImpl函数中为case&lt; -quit)并且函数返回。因此,在程序退出后,walkImpl函数中没有阻塞。