英文:
Go Channel and go routine with pointer variables all goroutines are asleep - deadlock
问题
我花了整个晚上来解决这个错误,但是没有成功。当我运行程序时,出现了以下错误:"所有的goroutine都处于休眠状态 - 死锁!"。我理解这是因为主程序在例程有机会执行任务之前就退出了,我原以为使用sync.WaitGroup会有所帮助,但实际上并没有解决问题。
我想设置一定数量的例程,并使用通道发送URL以检查HTTP状态码。我想限制对网站的并发调用数量。我已经按照使用字符串而不是结构体的示例进行了操作,它是有效的。
非常感谢任何帮助!
package main
import (
"fmt"
"sync"
"time"
)
const (
numPollers = 2 // 要启动的Poller goroutine数量
)
var urls = []string{
"http://www.google.com/",
"http://golang.org/",
"http://blog.golang.org/",
"http://golangtutorials.blogspot.fr",
"https://gobyexample.com/",
}
// Resource 表示此程序要轮询的HTTP URL。
type Resource struct {
url string
}
func Poller(in <-chan *Resource, wg *sync.WaitGroup) {
//defer wg.Done()
for r := range in {
fmt.Printf("Finished: %v - %v\n", r.url, time.Now())
}
wg.Done()
}
func main() {
var wg sync.WaitGroup
pending := make(chan *Resource)
wg.Add(len(urls))
go Poller(pending, &wg)
go func() {
for _, url := range urls {
wg.Add(1)
fmt.Println("SENT > Pending url " + url)
pending <- &Resource{url: url}
}
}()
wg.Wait()
fmt.Printf("Finished all goroutines: %v\n", time.Now())
}
链接:https://play.golang.org/p/B-HSiDo2Qg
英文:
I spend my evening looking at how to fix this error but I haven't succeeded. When I run the program I have the following error : "all goroutines are asleep - deadlock!". I understand this is because the main program is exited before the routine has the possibility to do its tasks and I thought using sync.WaitGroup would help but not really :/
I want to set a number of routine and use channels to send urls in order to check http status code. I want to limit the number of concurrency call to a website. I've followed examples doing the same thing with string instead of struct and it worked.
Any help would be well appreciated
package main
import (
"fmt"
"sync"
"time"
)
const (
numPollers = 2 // number of Poller goroutines to launch
)
var urls = []string{
"http://www.google.com/",
"http://golang.org/",
"http://blog.golang.org/",
"http://golangtutorials.blogspot.fr",
"https://gobyexample.com/",
}
// Resource represents an HTTP URL to be polled by this program.
type Resource struct {
url string
}
func Poller(in <-chan *Resource, wg *sync.WaitGroup) {
//defer wg.Done()
for r := range in {
fmt.Printf("Finished: %v - %v\n", r.url, time.Now())
}
wg.Done()
}
func main() {
var wg sync.WaitGroup
pending := make(chan *Resource)
wg.Add(len(urls))
go Poller(pending, &wg)
go func() {
for _, url := range urls {
wg.Add(1)
fmt.Println("SENT > Pending url " + url)
pending <- &Resource{url: url}
}
}()
wg.Wait()
fmt.Printf("Finished all goroutines: %v\n", time.Now())
}
答案1
得分: 3
首先,你对wg.Add()
的调用次数太多了。你为每个运行的goroutine调用了一次。请参考http://golang.org/pkg/sync/#WaitGroup。其次,在写入完成后,你没有关闭通道。这是你代码的修改版本:
package main
import (
"fmt"
"sync"
"time"
)
const (
numPollers = 2 // 要启动的Poller goroutine的数量
)
var urls = []string{
"http://www.google.com/",
"http://golang.org/",
"http://blog.golang.org/",
"http://golangtutorials.blogspot.fr",
"https://gobyexample.com/",
}
// Resource 表示此程序要轮询的HTTP URL。
type Resource struct {
url string
}
func Poller(in <-chan *Resource, wg *sync.WaitGroup) {
defer wg.Done()
for r := range in {
fmt.Printf("Finished: %v - %v\n", r.url, time.Now())
}
}
func main() {
var wg sync.WaitGroup
pending := make(chan *Resource)
wg.Add(numPollers)
go Poller(pending, &wg)
go func() {
defer close(pending)
defer wg.Done()
for _, url := range urls {
fmt.Println("SENT > Pending url " + url)
pending <- &Resource{url: url}
}
}()
wg.Wait()
fmt.Printf("Finished all goroutines: %v\n", time.Now())
}
和 https://play.golang.org/p/ucUlZEZMZM
英文:
First, you have too many calls to wg.Add()
. You call that once for each goroutine you're running. See http://golang.org/pkg/sync/#WaitGroup. Second, you didn't close the channel after you were done writing to it. Here's a modified version of your code:
package main
import (
"fmt"
"sync"
"time"
)
const (
numPollers = 2 // number of Poller goroutines to launch
)
var urls = []string{
"http://www.google.com/",
"http://golang.org/",
"http://blog.golang.org/",
"http://golangtutorials.blogspot.fr",
"https://gobyexample.com/",
}
// Resource represents an HTTP URL to be polled by this program.
type Resource struct {
url string
}
func Poller(in <-chan *Resource, wg *sync.WaitGroup) {
defer wg.Done()
for r := range in {
fmt.Printf("Finished: %v - %v\n", r.url, time.Now())
}
}
func main() {
var wg sync.WaitGroup
pending := make(chan *Resource)
wg.Add(2)
go Poller(pending, &wg)
go func() {
defer close(pending)
defer wg.Done()
for _, url := range urls {
fmt.Println("SENT > Pending url " + url)
pending <- &Resource{url: url}
}
}()
wg.Wait()
fmt.Printf("Finished all goroutines: %v\n", time.Now())
}
答案2
得分: 1
你忘记关闭通道,并且你的等待组时间太长。这个链接对我有用:https://play.golang.org/p/yasIzaCbmQ
英文:
You forget to close channel, and your wait group is too long. This works for me: https://play.golang.org/p/yasIzaCbmQ
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