There is the following code, the use of which leads to an infinite loop. The values from the channel are correct, the value of the variable sum is also correct. All the goroutines end up without errors.
func responseHandler(w http.ResponseWriter, r *http.Request) {
var c = make(chan string)
for i := 0; i < 100; i++ {
url := fmt.Sprintf("someurl/page%v/etc", i)
go parse(url, i, c)
if i%5 == 0 {
time.Sleep(1000 * time.Millisecond)
}
}
for range c {
sum = append(sum, <-c)
}
fmt.Println("Exit from channel wait")
fmt.Fprintln(w, sum)
}
func parse(url string, num int, c chan string) {
response, err1 := http.Get(url)
if err1 != nil {
log.Fatal(err1)
}
defer response.Body.Close()
if response.StatusCode != 200 {
log.Fatalf("status code error: %d %s", response.StatusCode,
response.Status)
}
res, err := DecodeHTMLBody(response.Body, "windows-1251")
doc, err := goquery.NewDocumentFromReader(res)
if err != nil {
log.Fatal(err)
}
doc.Find(".b-advItem__content").Each(func(i int, s *goquery.Selection) {
title := strings.TrimSpace(s.Find(".someclass").Text())
price := strings.TrimSpace(s.Find(".someclass").Text())
formatPrice := parsePrice(price)
c <- fmt.Sprintf("output %d: %s:%s
", i, title, formatPrice)
})
fmt.Printf("Channel %d - exit
", num)
Sum - global []string.
The range statement over a channel exits only when the channel is closed (well, think about it: how the range would otherwise detect there's no more data to fetch?), and nothing closes the channel in your code.
func responseHandler(w http.ResponseWriter, r *http.Request) {
...
for range c {
sum = append(sum, <-c)
if len(aa) == 100 {
close(c)
}
fmt.Fprintln(w, sum)
}
func parse(...){
...
aa = append(aa, num)
}
Adding such a check allows you to exit the loop correctly