Golang http.Post离开套接字

Question

I have the following golang code which when invoked inside of it's own webserver, appears to not close the socket. This leads to a "too many open files" message. I have read all about the Body.Close() stuff and as you can see it's in there, yet it still acts poorly.

What else am I missing about connection handling?

func sendRequest(ctx context.Context, endpoint, uri string, data []byte) (int, []byte) {
    reqID := requestIDFromContext(ctx)
    // The servers have internally signed certs which are technically "not trusted"
    tr := &http.Transport{
        TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
    }
    insecureclient := &http.Client{Transport: tr}

    // Build the correct URL
    url := endpoint + uri

    requestbody := bytes.NewBuffer(data)
    // Send our request and check for errors.
    fmt.Println(reqID, "Forwarding request to URL:", url)
    resp, err := insecureclient.Post(url, "application/json", requestbody)
    if err != nil {
        // This is where things happen when the connect goes bad
        fmt.Println(reqID, err)
        return 500, []byte("{}")
        //return handleConnectionError(ctx, data, uri)
    }
    defer resp.Body.Close()

    // Read response
    responsebody, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Println(reqID, err)
        responsebody = []byte("{}")
    }

    return resp.StatusCode, responsebody
}

FWIW, altering the code to use a 'http.NewRequest' and then an 'insecureclient.Do' along with a 'Request.Close = true' seems to fix the problem.

Answer 1

Each client (more precisely, transport) maintains its own connection pool. This means there is one connection "hanging" in keep-alive after each sendRequest call. Instead of creating a new client every time, re-use it.