英文:
Golang: Cannot send error to channel in recover()
问题
我尝试在恢复通道中发送一个错误，为什么这个错误没有发送到通道？
package main
import (
"fmt"
"sync"
"errors"
)
func main() {
var wg sync.WaitGroup
wg.Add(1)
batchErrChan := make(chan error)
go func(errchan chan error) {
defer func() {
if r := recover(); r != nil {
errchan <- errors.New("recover err")
}
close(batchErrChan)
wg.Done()
}()
panic("ddd")
}(batchErrChan)
go func() {
for _ = range batchErrChan {
fmt.Println("err in range")
}
}()
wg.Wait()
}
我期望会打印出"err in range"，但实际上没有打印出来。为什么呢？
英文:
I try to send an error in the channel on recovery
Why this error is not sent to the channel?
package main
import (
"fmt"
"sync"
"errors"
)
func main() {
var wg sync.WaitGroup
wg.Add(1)
batchErrChan := make(chan error)
go func(errchan chan error) {
defer func() {
if r := recover(); r != nil {
errchan <- errors.New("recover err")
}
close(batchErrChan)
wg.Done()
}()
panic("ddd")
}(batchErrChan)
go func() {
for _ = range batchErrChan {
fmt.Println("err in range")
}
}()
wg.Wait()
}
https://play.golang.org/p/0ytunuYDWZU
I expect "err in range" to be printed, but it is not. Why?
答案1
得分: 3
你的程序在goroutine有机会打印消息之前就结束了。尝试等待它：
...
done := make(chan struct{})
go func() {
for _ = range batchErrChan {
fmt.Println("err in range")
}
close(done)
}()
wg.Wait()
<-done
}
你可以将以上代码添加到你的程序中，以确保在等待goroutine完成之后再结束程序。
英文:
Your program ends before the goroutine gets a chance to print the message. Try waiting to it:
...
done:=make(chan struct{})
go func() {
for _ = range batchErrChan {
fmt.Println("err in range")
}
close(done)
}()
wg.Wait()
<-done
}
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