套接字无法识别协议(套接字泄漏)

Question

我有一个Go1.5.1进程/应用程序。当我在那个进程上运行/usr/sbin/lsof -p时，我看到很多"无法识别协议"。

monitor_ 13105 root  101u  sock      0,6      0t0 16960100 can't identify protocol
monitor_ 13105 root  102u  sock      0,6      0t0 21552427 can't identify protocol
monitor_ 13105 root  103u  sock      0,6      0t0 17565091 can't identify protocol
monitor_ 13105 root  104u  sock      0,6      0t0 18476870 can't identify protocol

proc状态/限制/fd

[root@Monitor_q ~]# cat /proc/13105/status 
Name:   monitor_client
State:  S (sleeping)
Tgid:   13105
Pid:    13105
PPid:   13104
TracerPid:  0
Uid:    0   0   0   0
Gid:    0   0   0   0
Utrace: 0
FDSize: 16384
Groups: 
...

[root@Monitor_q ~]# cat /proc/13105/limits 
Limit                     Soft Limit           Hard Limit           Units     
Max cpu time              unlimited            unlimited            seconds   
Max file size             unlimited            unlimited            bytes     
Max data size             unlimited            unlimited            bytes     
Max stack size            10485760             unlimited            bytes     
Max core file size        0                    unlimited            bytes     
Max resident set          unlimited            unlimited            bytes     
Max processes             3870                 3870                 processes 
Max open files            9999                 9999                 files     
Max locked memory         65536                65536                bytes     
Max address space         unlimited            unlimited            bytes     
Max file locks            unlimited            unlimited            locks     
Max pending signals       3870                 3870                 signals   
Max msgqueue size         819200               819200               bytes     
Max nice priority         0                    0                    
Max realtime priority     0                    0                    
Max realtime timeout      unlimited            unlimited            us
[root@Monitor_q ~]# ll /proc/13105/fd/
lrwx------ 1 root root 64 Dec  7 00:15 8382 -> socket:[52023221]
lrwx------ 1 root root 64 Dec  7 00:15 8383 -> socket:[51186627]
lrwx------ 1 root root 64 Dec  7 00:15 8384 -> socket:[51864232]
lrwx------ 1 root root 64 Dec  7 00:15 8385 -> socket:[52435453]
lrwx------ 1 root root 64 Dec  7 00:15 8386 -> socket:[51596071]
lrwx------ 1 root root 64 Dec  7 00:15 8387 -> socket:[52767667]
lrwx------ 1 root root 64 Dec  7 00:15 8388 -> socket:[52090632]
lrwx------ 1 root root 64 Dec  7 00:15 8389 -> socket:[51739068]
lrwx------ 1 root root 64 Dec  7 00:15 839 -> socket:[22963529]
lrwx------ 1 root root 64 Dec  7 00:15 8390 -> socket:[52023223]
lrwx------ 1 root root 64 Dec  7 00:15 8391 -> socket:[52560389]
lrwx------ 1 root root 64 Dec  7 00:15 8392 -> socket:[52402565]
...

但在CCD_ 2中没有类似的输出。

这些插座是什么？我怎样才能知道它们的作用？

monitor_client.go

package main
import (
    "crypto/tls"
    "encoding/json"
    "fmt"
    "log"
    "net"
    "net/http"
    nurl "net/url"
    "strconv"
    "strings"
    "syscall"
    "time"
)
type Result struct {
    Error      string        `json:"error"`
    HttpStatus int           `json:"http_status"`
    Stime      time.Duration `json:"http_time"`
}
//http://stackoverflow.com/questions/20990332/golang-http-timeout-and-goroutines-accumulation
//http://3.3.3.3/http?host=3.2.4.2&servername=a.test&path=/&port=33&timeout=5&scheme=http
func MonitorHttp(w http.ResponseWriter, r *http.Request) {
    var host, servername, path, port, scheme string
    var timeout int
    u, err := nurl.Parse(r.RequestURI)
    if err != nil {
        log.Fatal(err)
        return
    }
    if host = u.Query().Get("host"); host == "" {
        host = "127.0.0.0"
    }
    if servername = u.Query().Get("servername"); servername == "" {
        servername = "localhost"
    }
    if path = u.Query().Get("path"); path == "" {
        path = "/"
    }
    if port = u.Query().Get("port"); port == "" {
        port = "80"
    }
    if scheme = u.Query().Get("scheme"); scheme == "" {
        scheme = "http"
    }
    if timeout, _ = strconv.Atoi(u.Query().Get("timeout")); timeout == 0 {
        timeout = 5
    }
    //log.Printf("(host)=%s (servername)=%s (path)=%s (port)=%s (timeout)=%d", host, servername, path, port, timeout)
    w.Header().Set("Content-Type", "application/json")
    res := httptool(host, port, servername, scheme, path, timeout)
    result, _ := json.Marshal(res)
    fmt.Fprintf(w, "%s", result)
}
func httptool(ip, port, servername, scheme, path string, timeout int) Result {
    var result Result
    startTime := time.Now()
    host := ip + ":" + port
    transport := &http.Transport{
        TLSClientConfig:   &tls.Config{InsecureSkipVerify: true},
        DisableKeepAlives: true,
    }
    dialer := net.Dialer{
        Timeout:   time.Duration(timeout) * time.Second,
        KeepAlive: 0 * time.Second,
    }
    transport.Dial = func(network, address string) (net.Conn, error) {
        return dialer.Dial(network, address)
    }
    client := &http.Client{
        Transport: transport,
    }
    rawquery := ""
    url := fmt.Sprintf("%s://%s%s%s", scheme, host, path, rawquery)
    req, err := http.NewRequest("GET", url, nil)
    if err != nil {
        result.HttpStatus = -1
        errs := strings.Split(err.Error(), ": ")
        result.Error = errs[len(errs)-1]
        result.Stime = time.Now().Sub(startTime) / time.Millisecond
        return result
    }
    req.Header.Set("User-Agent", "monitor worker")
    req.Header.Set("Connection", "close")
    req.Host = servername
    resp, err := client.Do(req)
    //https://github.com/Basiclytics/neverdown/blob/master/check.go
    if err != nil {
        nerr, ok := err.(*nurl.Error)
        if ok {
            switch cerr := nerr.Err.(type) {
            case *net.OpError:
                switch cerr.Err.(type) {
                case *net.DNSError:
                    errs := strings.Split(cerr.Error(), ": ")
                    result.Error = "dns: " + errs[len(errs)-1]
                default:
                    errs := strings.Split(cerr.Error(), ": ")
                    result.Error = "server: " + errs[len(errs)-1]
                }
            default:
                switch nerr.Err.Error() {
                case "net/http: request canceled while waiting for connection":
                    errs := strings.Split(cerr.Error(), ": ")
                    result.Error = "timeout: " + errs[len(errs)-1]
                default:
                    errs := strings.Split(cerr.Error(), ": ")
                    result.Error = "unknown: " + errs[len(errs)-1]
                }
            }
        } else {
            result.Error = "unknown: " + err.Error()
        }
        result.HttpStatus = -2
        result.Stime = time.Now().Sub(startTime) / time.Millisecond
        return result
    }
    resp.Body.Close()
    result.HttpStatus = resp.StatusCode
    result.Error = "noerror"
    result.Stime = time.Now().Sub(startTime) / time.Millisecond //spend time (ms)
    return result
}
func setRlimit() {
    var rLimit syscall.Rlimit
    err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
    if err != nil {
        log.Printf("Unable to obtain rLimit", err)
    }
    if rLimit.Cur < rLimit.Max {
        rLimit.Max = 9999
        rLimit.Cur = 9999
        err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
        if err != nil {
            log.Printf("Unable to increase number of open files limit", err)
        }
    }
}
func main() {
    setRlimit()
    s := &http.Server{
        Addr:         ":59059",
        ReadTimeout:  7 * time.Second,
        WriteTimeout: 7 * time.Second,
    }
    http.HandleFunc("/http", MonitorHttp)
    log.Fatal(s.ListenAndServe())
}

Answer 1

这里有几个要点。

我无法重现您的行为，无论如何，can't identify protocol通常与未正确关闭的套接字有关。

一些评论者建议您不必在每个处理程序中创建http客户端，这是真的。只需创建一次并重复使用即可。

其次，我不确定为什么要创建自己的http.Client结构，以及为什么要禁用keepalives。你就不能选择http.Get吗？更简单的代码更容易调试。

第三，不确定为什么要重写transport.Dial函数。即使你必须这样做，文档（Go 1.9.2）上写着：

% go doc http.transport.dial
type Transport struct {
    // Dial specifies the dial function for creating unencrypted TCP
    connections.
    //
    // Deprecated: Use DialContext instead, which allows the transport
    // to cancel dials as soon as they are no longer needed.
    // If both are set, DialContext takes priority.
    Dial func(network, addr string) (net.Conn, error)

关于弃用和缺少拨号盘重用的评论可能会指出问题的根源。

总之，当我站在你的立场上时，我会做两件事：

• 将客户端创建移到执行一次的代码中，或者只使用默认客户端http.Get
• 我会通过覆盖默认传输字段来清理这件事，如果必须这样做，那么我会按照建议使用DialContext

祝你好运。

Answer 2

我无法重现该问题。但这是我的2美分（并非双关语）

1. 在一篇文章中注意到的SockJS节点中发现了Simmilar问题https://idea.popcount.org/2012-12-09-lsof-cant-identify-protocol/根据这个问题，在FreeBSD上观察到了。但问题是"网络套接字没有得到妥善清理"
2. 另一个测试，我希望你们做，若你们仍然有手在相同的环境。如果可能，张贴wireshark日志。只是为了确认网络帧中没有细微的事情可能导致了这种情况

很抱歉，我不能仅仅为了重现这个问题而安装Go 1.5.1。希望这有帮助。