Go Flush() doesn't work

Question

Please, check this gist and tell me, what's wrong?
Why I don't see my messages?
The gist: https://gist.github.com/cnaize/895f61b762a9f5ee074c

If simple, I have two functions:

func send(param martini.Params, r render.Render) {
    Ct.Msgs <- param["msg"]

    fmt.Printf("Sent: %v", param["msg"])

    r.JSON(http.StatusOK, Response{"status": "ok"})
}

And watch function:

func watch(rw http.ResponseWriter, r render.Render) {
    var msg string
    ok := true
    for ok {
        select {
        case msg, ok = <-Ct.Msgs:
            rw.Write([]byte(msg))
            fmt.Printf("Wrote: %v", msg)
            f, ok := rw.(http.Flusher)
            if ok {
                f.Flush()
                fmt.Println("Flushed")
            } else {
                r.JSON(http.StatusOK, Response{"status": "error", "descr": "CANT_FLUSH"})
                return
            }
        }
    }

    r.JSON(http.StatusOK, Response{"status": "ok", "descr": "finished"})
}

Why it doesn't work?

EDITED:

I've updated my gist. Now where are:

if i, err := rw.Write([]byte(msg)); err != nil {
    r.JSON(http.StatusOK, Response{"status": "error", "descr": err.Error()})
    return
} else {
    fmt.Printf("i: %v", i)
}

And I have in logs:

 Sent: hello
 i: 5
 Wrote: hello
 Flushed

But I see nothing.

Any ideas?

Answer 1

The flush is working. The issue is that Chrome's plain text renderer waits for the complete response body before displaying anything. Force the content type to html to see the incremental response:

func watch(rw http.ResponseWriter, r render.Render) {
    rw.Header().Set("Content-Type", "text/html")
    // same code as before
}