问题描述
我有一个 Go 程序,它从多个 goroutine 生成大量 HTTP 请求.运行一会,程序吐出一个错误:connect:cannotassignrequested address.
I have a Go program that generates a lot of HTTP requests from multiple goroutines. after running for a while, the program spits out an error: connect: cannot assign requested address.
在使用 netstat
进行检查时,我在 TIME_WAIT
中获得大量连接 (28229).
When checking with netstat
, I get a high number (28229) of connections in TIME_WAIT
.
TIME_WAIT
套接字的大量发生在 goroutine 的数量为 3 时发生,并且严重到足以导致崩溃时为 5.
The high number of TIME_WAIT
sockets happens when I the number of goroutines is 3 and is severe enough to cause a crash when it is 5.
我在 docker 下运行 Ubuntu 14.4 并使用 1.7 版
I run Ubuntu 14.4 under docker and go version 1.7
这是 Go 程序.
package main
import (
"io/ioutil"
"log"
"net/http"
"sync"
)
var wg sync.WaitGroup
var url="http://172.17.0.9:3000/";
const num_coroutines=5;
const num_request_per_coroutine=100000
func get_page(){
response, err := http.Get(url)
if err != nil {
log.Fatal(err)
} else {
defer response.Body.Close()
_, err =ioutil.ReadAll(response.Body)
if err != nil {
log.Fatal(err)
}
}
}
func get_pages(){
defer wg.Done()
for i := 0; i < num_request_per_coroutine; i++{
get_page();
}
}
func main() {
for i:=0;i<num_coroutines;i++{
wg.Add(1)
go get_pages()
}
wg.Wait()
}
这是服务器程序:
package main
import (
"fmt"
"net/http"
"log"
)
var count int;
func sayhelloName(w http.ResponseWriter, r *http.Request) {
count++;
fmt.Fprintf(w,"Hello World, count is %d",count) // send data to client side
}
func main() {
http.HandleFunc("/", sayhelloName) // set router
err := http.ListenAndServe(":3000", nil) // set listen port
if err != nil {
log.Fatal("ListenAndServe: ", err)
}
}
推荐答案
默认的 http.Transport 打开和关闭连接的速度太快.由于所有连接都指向相同的主机:端口组合,您需要增加 MaxIdleConnsPerHost
以匹配您的 num_coroutines
值.否则,传输将经常关闭额外的连接,然后立即重新打开它们.
The default http.Transport is opening and closing connections too quickly. Since all connections are to the same host:port combination, you need to increase MaxIdleConnsPerHost
to match your value for num_coroutines
. Otherwise, the transport will frequently close the extra connections, only to have them reopened immediately.
您可以在默认传输上全局设置:
You can set this globally on the default transport:
http.DefaultTransport.(*http.Transport).MaxIdleConnsPerHost = numCoroutines
或者在创建自己的传输时
Or when creating your own transport
t := &http.Transport{
Proxy: http.ProxyFromEnvironment,
DialContext: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
}).DialContext,
MaxIdleConnsPerHost: numCoroutines,
MaxIdleConns: 100,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
}
这篇关于Go 客户端程序生成大量 TIME_WAIT 状态的套接字的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!