Go 使用 http 连接 fd 泄露问题

麦壳

模拟一下，服务端：
// gohttperver.gopackage mainimport ( "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))}// gohttpclient.gopackage mainimport ( "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 gohttperver.go &$ go run gohttpclient.go &查看连接数：
$ netstat -an |grep 9901 | grep ESTABLISHEDtcp4 0 0 127.0.0.1.9901 127.0.0.1.54403 ESTABLISHEDtcp4 0 0 127.0.0.1.54403 127.0.0.1.9901 ESTABLISHEDtcp4 0 0 127.0.0.1.9901 127.0.0.1.54402 ESTABLISHEDtcp4 0 0 127.0.0.1.54402 127.0.0.1.9901 ESTABLISHEDtcp4 0 0 127.0.0.1.9901 127.0.0.1.54398 ESTABLISHEDtcp4 0 0 127.0.0.1.54398 127.0.0.1.9901 ESTABLISHEDtcp4 0 0 127.0.0.1.9901 127.0.0.1.54397 ESTABLISHEDtcp4 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 connectiongoogle golang http.Request close查看指定进程的连接信息
# ps -ef|grep rigroot 4865 4258 0 11:30 pts/0 00:00:00 grep --color=auto rigfootsto+ 14995 1 0 11月12 ? 00:07:29 ./rig_linux_amd64 -ufootsto+ 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-serverrigaga 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 14995COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAMErig_linux 14995 footstone cwd DIR 253,1 4096 2818080 /home/footstone/go-opads/ops-rig/20191112-1573526761rig_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_amd64rig_linux 14995 footstone mem REG 253,1 2173512 328343 /usr/lib64/libc-2.17.sorig_linux 14995 footstone mem REG 253,1 144792 328369 /usr/lib64/libpthread-2.17.sorig_linux 14995 footstone mem REG 253,1 164240 328336 /usr/lib64/ld-2.17.sorig_linux 14995 footstone 0r CHR 1,3 0t0 1028 /dev/nullrig_linux 14995 footstone 1w REG 253,1 1179657 2818128 /home/footstone/go-opads/ops-rig/20191112-1573526761/nohup.outrig_linux 14995 footstone 2w REG 253,1 1179657 2818128 /home/footstone/go-opads/ops-rig/20191112-1573526761/nohup.outrig_linux 14995 footstone 3r a_inode 0,9 0 5937 inotifyrig_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 piperig_linux 14995 footstone 7w FIFO 0,8 0t0 1441054004 piperig_linux 14995 footstone 8w CHR 1,3 0t0 1028 /dev/nullrig_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/var/rig_linux_amd64.log.201911260000
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