Go 使用 http 连接 fd 泄露问题
时间：12-14来源：作者：点击数：
模拟一下，服务端：
// gohttpserver.go
package main
import (
"fmt"
"log"
"net/http"
"time"
)
func main() {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Hi there, say I love you! current time %v", time.Now())
})
log.Fatal(http.ListenAndServe(":9901", nil))
}
客户端：
// gohttpclient.go
package main
import (
"fmt"
"io/ioutil"
"net"
"net/http"
"time"
)
func main() {
url := "http://127.0.0.1:9901"
for i := 0; i < 10000; i++ {
func() {
trans := &http.Transport{
DialContext: (&net.Dialer{
Timeout: 3 * time.Second,
KeepAlive: 30 * time.Second,
}).DialContext,
ForceAttemptHTTP2: true,
MaxIdleConns: 100,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
}
//defer trans.CloseIdleConnections()
client := &http.Client{
Timeout: time.Duration(100) * time.Millisecond,
Transport: trans,
}
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return
}
//req.Close = true // fd leak without setting this
resp, err := client.Do(req)
if err != nil {
// handle error
}
defer resp.Body.Close()
haha, _ := ioutil.ReadAll(resp.Body)
fmt.Println(string(haha))
}()
time.Sleep(500 * time.Millisecond)
}
}
运行服务端和客户端
$ go run gohttpserver.go &
$ go run gohttpclient.go &
查看连接数：
$ netstat -an |grep 9901 | grep ESTABLISHED
tcp4 0 0 127.0.0.1.9901 127.0.0.1.54403 ESTABLISHED
tcp4 0 0 127.0.0.1.54403 127.0.0.1.9901 ESTABLISHED
tcp4 0 0 127.0.0.1.9901 127.0.0.1.54402 ESTABLISHED
tcp4 0 0 127.0.0.1.54402 127.0.0.1.9901 ESTABLISHED
tcp4 0 0 127.0.0.1.9901 127.0.0.1.54398 ESTABLISHED
tcp4 0 0 127.0.0.1.54398 127.0.0.1.9901 ESTABLISHED
tcp4 0 0 127.0.0.1.9901 127.0.0.1.54397 ESTABLISHED
tcp4 0 0 127.0.0.1.54397 127.0.0.1.9901 ESTABLISHED
然后放开客户端的defer trans.CloseIdleConnections()或者req.Close = true，重新运行，都可以修复此问题。
查看源代码 net/http/client.go，可以找到
func (c *Client) transport() RoundTripper {
if c.Transport != nil {
return c.Transport
}
return DefaultTransport
}
然后在 net/http/transport.go 中，继续看，连接池是挂在 Transport 上，所以每次新建 Transport，如果不关闭，就会导致连接泄露。
// DefaultTransport is the default implementation of Transport and is
// used by DefaultClient. It establishes network connections as needed
// and caches them for reuse by subsequent calls. It uses HTTP proxies
// as directed by the $HTTP_PROXY and $NO_PROXY (or $http_proxy and
// $no_proxy) environment variables.
var DefaultTransport RoundTripper = &Transport{
Proxy: ProxyFromEnvironment,
DialContext: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
DualStack: true,
}).DialContext,
ForceAttemptHTTP2: true,
MaxIdleConns: 100,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
}
// ...
type Transport struct {
idleMu sync.Mutex
closeIdle bool // user has requested to close all idle conns
idleConn map[connectMethodKey][]*persistConn // most recently used at end
idleConnWait map[connectMethodKey]wantConnQueue // waiting getConns
idleLRU connLRU
reqMu sync.Mutex
reqCanceler map[*Request]func(error)
altMu sync.Mutex // guards changing altProto only
altProto atomic.Value // of nil or map[string]RoundTripper, key is URI scheme
connsPerHostMu sync.Mutex
connsPerHost map[connectMethodKey]int
connsPerHostWait map[connectMethodKey]wantConnQueue // waiting getConns
// ...
}
感谢：
- golang http client 关闭重用连接两种方法
- 如何关闭 Golang 中的 HTTP 连接 How to Close Golang's HTTP connection
- google golang http.Request close
查看指定进程的连接信息
# ps -ef|grep rig
root 4865 4258 0 11:30 pts/0 00:00:00 grep --color=auto rig
footsto+ 14995 1 0 11月12 ? 00:07:29 ./rig_linux_amd64 -u
footsto+ 15459 1 0 10月18 ? 00:45:26 java -server -Xmx768m -Xms768m -Xmn384m -XX:PermSize=128m -Xss256k -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:+UseCMSCompactAtFullCollection -XX:LargePageSizeInBytes=128m -XX:+UseFastAccessorMethods -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=70 -Dlogpath.base=/home/footstone/logs/bjca-app-rig-metrics-server -cp /home/footstone/YUQI_TEST/config:/home/footstone/YUQI_TEST/lib/* -jar /home/footstone/YUQI_TEST/lib/rig-metrics-server-1.0.0-SNAPSHOT.jar bjca-app-rig-metrics-server
rigaga 20730 1 0 9月25 ? 03:30:40 /usr/bin/rigaga -config /etc/rigaga/rigaga.conf -config-directory /etc/rigaga/rigaga.d
# lsof -p 14995
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
rig_linux 14995 footstone cwd DIR 253,1 4096 2818080 /home/footstone/go-opads/ops-rig/20191112-1573526761
rig_linux 14995 footstone rtd DIR 253,1 4096 2 /
rig_linux 14995 footstone txt REG 253,1 22682823 2818082 /home/footstone/go-opads/ops-rig/20191112-1573526761/rig_linux_amd64
rig_linux 14995 footstone mem REG 253,1 2173512 328343 /usr/lib64/libc-2.17.so
rig_linux 14995 footstone mem REG 253,1 144792 328369 /usr/lib64/libpthread-2.17.so
rig_linux 14995 footstone mem REG 253,1 164240 328336 /usr/lib64/ld-2.17.so
rig_linux 14995 footstone 0r CHR 1,3 0t0 1028 /dev/null
rig_linux 14995 footstone 1w REG 253,1 1179657 2818128 /home/footstone/go-opads/ops-rig/20191112-1573526761/nohup.out
rig_linux 14995 footstone 2w REG 253,1 1179657 2818128 /home/footstone/go-opads/ops-rig/20191112-1573526761/nohup.out
rig_linux 14995 footstone 3r a_inode 0,9 0 5937 inotify
rig_linux 14995 footstone 4u a_inode 0,9 0 5937 [eventpoll]
rig_linux 14995 footstone 5u a_inode 0,9 0 5937 [eventpoll]
rig_linux 14995 footstone 6r FIFO 0,8 0t0 1441054004 pipe
rig_linux 14995 footstone 7w FIFO 0,8 0t0 1441054004 pipe
rig_linux 14995 footstone 8w CHR 1,3 0t0 1028 /dev/null
rig_linux 14995 footstone 10u IPv6 1441050975 0t0 TCP *:10099 (LISTEN)
rig_linux 14995 footstone 11w REG 253,1 29608321 2818151 /home/footstone/go-opads/ops-rig/20191112-1573526761方便获取更多学习、工作、生活信息请关注本站微信公众号
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