Demo of writing into a channel without reading from it.

sum_dont_read.go

package main

import (
        "fmt"
        "log"
        "net/http"
        "strconv"
)

// function to add an array of numbers.
func sum(s []int, c chan int) {
        sum := 0
        for _, v := range s {
                sum += v
        }
        // writes the sum to the go routines.
        c <- sum // send sum to c
}

// HTTP handler for /sum
func sumConcurrent(w http.ResponseWriter, r *http.Request) {
        s := []int{7, 2, 8, -9, 4, 0}

        c1 := make(chan int)
        c2 := make(chan int)
        // spin up a goroutine.
        go sum(s[:len(s)/2], c1)
        // spin up a goroutine.
        go sum(s[len(s)/2:], c2)
        // not reading from c2.
        // go routine writing to c2 will be blocked.
        x := <-c1
        // write the response.
        fmt.Fprintf(w, strconv.Itoa(x))
}

func main() {
        http.HandleFunc("/sum", sumConcurrent)   // set router
        err := http.ListenAndServe(":8001", nil) // set listen port
        if err != nil {
                log.Fatal("ListenAndServe: ", err)
        }
}