Using Channels in Go to receive Responses and Write to SQL Concurrently - go

Question

I am working with Go to implement a pipeline of JSON data from an external API, process the message and then send to a SQL database.
I am trying to concurrently run API requests, then after I return a response, I'd like to send it to be inserted into the DB via another goroutine via load().
In my below code, sometimes I'll receive my log.Printf() in the load() func, other times I won't. Which indicates that I'm likely closing a channel or not properly setting up the communication.
The pattern I am attempting is something like this:
package main
import (
"encoding/json"
"io/ioutil"
"log"
"net/http"
"time"
)
type Request struct {
url string
}
type Response struct {
status int
args Args `json:"args"`
headers Headers `json:"headers"`
origin string `json:"origin"`
url string `json:"url"`
}
type Args struct {
}
type Headers struct {
accept string `json:"Accept"`
}
func main() {
start := time.Now()
numRequests := 5
responses := make(chan Response, 5)
defer close(responses)
for i := 0; i < numRequests; i++ {
req := Request{url: "https://httpbin.org/get"}
go func(req *Request) {
resp, err := extract(req)
if err != nil {
log.Fatal("Error extracting data from API")
return
}
// Send response to channel
responses <- resp
}(&req)
// Perform go routine to load data
go load(responses)
}
log.Println("Execution time: ", time.Since(start))
}
func extract(req *Request) (r Response, err error) {
var resp Response
request, err := http.NewRequest("GET", req.url, nil)
if err != nil {
return resp, err
}
request.Header = http.Header{
"accept": {"application/json"},
}
response, err := http.DefaultClient.Do(request)
defer response.Body.Close()
if err != nil {
log.Fatal("Error")
return resp, err
}
// Read response data
body, err := ioutil.ReadAll(response.Body)
if err != nil {
log.Fatal("Error")
return resp, err
}
json.Unmarshal(body, &resp)
resp.status = response.StatusCode
return resp, nil
}
type Record struct {
origin string
url string
}
func load(ch chan Response) {
// Read response from channel
resp := <-ch
// Process the response data
records := process(resp)
log.Printf("%+v\n", records)
// Load data to db stuff here
}
func process(resp Response) (record Record) {
// Process the response struct as needed to get a record of data to insert to DB
return record
}

Answer 1

The program has no protection against completion before the work is done. So sometimes the program terminates before the goroutine can finish.
To prevent that, use a WaitGroup:
wg:=sync.WaitGroup{}
for i := 0; i < numRequests; i++ {
...
wg.Add(1)
go func() {
defer wg.Done()
load(responses)
}()
}
wg.Wait()