Golang long polling example

main.go

package main

import (
    "fmt"
    "net/http"
    "time"
)

func longOperation(ch chan<- string) {
    // Simulate long operation.
    // Change it to more than 10 seconds to get server timeout.
    time.Sleep(time.Second * 3)

    ch <- "Successful result."
}

func handler(w http.ResponseWriter, _ *http.Request) {
    ch := make(chan string)

    go longOperation(ch)

    select {
    case result := <-ch:
        fmt.Fprint(w, result)
    case <-time.After(time.Second * 10):
        fmt.Fprint(w, "Server is busy.")
        <-ch
    }

    close(ch)
}

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe("localhost:8080", nil)
}

for {
select {
case
}
}
will be better.