Challenge 1 - Concurrency
- Go course
- Intermediate
- Lesson 77/80
- 8 min
Write a program combining goroutines, channels and WaitGroup.
Challenge: a parallel word counter
You will write a program that processes several texts at once and finds the total word count. Each text is counted in its own goroutine, the results are collected on a channel, and the end of all goroutines is awaited with a sync.WaitGroup.
metinler := []string{
"go hızlı ve basit",
"kanallar goroutine'leri bağlar",
"eşzamanlılık paralellik değildir",
}
// expected total: 10Use strings.Fields to count words; it handles multiple spaces and newlines correctly.
Plan
1) sonuc := make(chan int, len(metinler)) — a buffer with room for every goroutine. 2) For each text, wg.Add(1) + a goroutine: sonuc <- len(strings.Fields(m)). 3) wg.Wait(), then close(sonuc). 4) Sum with for n := range sonuc. Thanks to the buffer, Wait and close can safely happen in the same goroutine.
Practice Write the counter
Write the program following the plan and print the total word count.
Starter code
package main
import (
"fmt"
"strings"
"sync"
)
func main() {
// buraya yaz
}Sample solution
package main
import (
"fmt"
"strings"
"sync"
)
func main() {
metinler := []string{
"go hızlı ve basit",
"kanallar goroutine'leri bağlar",
"eşzamanlılık paralellik değildir",
}
sonuc := make(chan int, len(metinler))
var wg sync.WaitGroup
for _, m := range metinler {
wg.Add(1)
go func(m string) {
defer wg.Done()
sonuc <- len(strings.Fields(m))
}(m)
}
wg.Wait()
close(sonuc)
toplam := 0
for n := range sonuc {
toplam += n
}
fmt.Println(toplam)
}Expected output
10
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How many elements does <code>strings.Fields(" a b ")</code> return?
- 2 Correct answer
- 5
- 3
- 7
Explanation: Fields treats consecutive spaces as one separator and drops leading/trailing spaces; Split(" ") would produce empty pieces.
2 Split the words
n := len(strings.____(metin))n := len(strings.Fields(metin))Explanation: strings.Fields splits text into words by whitespace.
3 Piece and role
| Term | Meaning |
|---|---|
goroutine |
Counts one text |
The sonuc channel |
Carries the counts |
wg.Wait |
Waits for all to finish |
range sonuc |
Sums |