[英]golang http timeout and goroutines accumulation
我使用goroutines实现http.Get超时,然后我发现goroutines的数量一直在稳定增长,当达到1000左右时,程序将退出
码:
package main
import (
"errors"
"io/ioutil"
"log"
"net"
"net/http"
"runtime"
"time"
)
// timeout dialler
func timeoutDialler(timeout time.Duration) func(network, addr string) (net.Conn, error) {
return func(network, addr string) (net.Conn, error) {
return net.DialTimeout(network, addr, timeout)
}
}
func timeoutHttpGet(url string) ([]byte, error) {
// change dialler add timeout support && disable keep-alive
tr := &http.Transport{
Dial: timeoutDialler(3 * time.Second),
DisableKeepAlives: true,
}
client := &http.Client{Transport: tr}
type Response struct {
resp []byte
err error
}
ch := make(chan Response, 0)
defer func() {
close(ch)
ch = nil
}()
go func() {
resp, err := client.Get(url)
if err != nil {
ch <- Response{[]byte{}, err}
return
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
ch <- Response{[]byte{}, err}
return
}
tr.CloseIdleConnections()
ch <- Response{body, err}
}()
select {
case <-time.After(5 * time.Second):
return []byte{}, errors.New("timeout")
case response := <-ch:
return response.resp, response.err
}
}
func handler(w http.ResponseWriter, r *http.Request) {
_, err := timeoutHttpGet("http://google.com")
if err != nil {
log.Println(err)
return
}
}
func main() {
go func() {
for {
log.Println(runtime.NumGoroutine())
time.Sleep(500 * time.Millisecond)
}
}()
s := &http.Server{
Addr: ":8888",
ReadTimeout: 15 * time.Second,
WriteTimeout: 15 * time.Second,
}
http.HandleFunc("/", handler)
log.Fatal(s.ListenAndServe())
}
用1而不是0初始化chan:
ch := make(chan Response, 1)
并删除关闭并延迟ch的延迟块。
参见: http : //blog.golang.org/go-concurrency-patterns-timing-out-and
我认为这是正在发生的事情:
我假设您设置ch = nil
因为在您拥有ch = nil
之前,您会遇到运行时恐慌,因为这是您尝试写入规范中所述的封闭通道时发生的情况。
给ch一个1的缓冲区意味着fetch go例程可以发送给它而无需接收者。 如果处理程序由于超时而返回,则稍后将收集所有垃圾。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.