Why concurrency is needed in Go - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a new goroutine.

Go

go [1]()

Drag options to blanks, or click blank then click option'

Afmt.Println

Bmain

CsayHello

Dtime.Sleep

Attempts:

3 left

💡 Hint

Common Mistakes

Using fmt.Println directly after go without calling a function.

Trying to start the main function as a goroutine.

Using time.Sleep without parentheses.

The go keyword starts a new goroutine running the function sayHello.

2fill in blank

medium

Complete the code to wait for a goroutine to finish using a channel.

Go

done := make(chan bool)
go func() {
    fmt.Println("Working...")
    done [1] true
}()
<-done

Drag options to blanks, or click blank then click option'

A<-

B<-chan

D<-chan bool

Attempts:

3 left

💡 Hint

Common Mistakes

Using the receive operator <- on the left side incorrectly.

Confusing channel type declarations with send/receive operations.

To send a value to a channel, use done <- true.

3fill in blank

hard

Fix the error in the code to correctly launch multiple goroutines.

Go

for i := 0; i < 3; i++ {
    go func() {
        [1]
        fmt.Println(i)
    }()
}

Drag options to blanks, or click blank then click option'

Avar i

Bi

Ci int

Di := i

Attempts:

3 left

💡 Hint

Common Mistakes

Not capturing the loop variable causes all goroutines to print the same value.

Trying to declare i with a type inside the loop incorrectly.

Passing i as a parameter inside the goroutine fixes the closure capturing issue.

4fill in blank

hard

Fill both blanks to create a buffered channel and send a value.

Go

ch := make(chan int, [1])
ch [2] 5

Drag options to blanks, or click blank then click option'

A1

B<-

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero as buffer size creates an unbuffered channel.

Using the receive operator instead of send operator.

A buffered channel of size 1 is created, then the value 5 is sent using ch <- 5.

5fill in blank

hard

Fill all three blanks to create a map with word lengths using concurrency.

Go

words := []string{"go", "code", "fun"}
lengths := make(map[string]int)
var mu sync.Mutex
for _, word := range words {
    go func(w string) {
        mu.Lock()
        lengths[[1]] = len([2])
        mu.Unlock()
    }([3])
}

Drag options to blanks, or click blank then click option'

Aw

Cword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the loop variable word directly inside the goroutine causes race conditions.

Not locking the map before writing causes concurrent map writes error.

The goroutine uses the parameter w to safely update the map with the length of each word.