How to Pass a Go Interview: Top Questions from A to Z

How to Pass a Go Interview: Top Questions from A to Z

A Go developer interview is not just a syntax check. Employers look for candidates who understand the language's philosophy: simplicity, concurrency, and efficient memory management. In this article, we'll break down the key questions you'll definitely be asked — from the basics to advanced topics with code examples. Prepare using our checklist, and you'll feel confident.

1. Go Basics: Data Types, Structures, and Memory Management

Let's start with the fundamentals. You can't get anywhere without them. Interviewers love to ask questions about types and their behavior.

What built-in data types exist in Go?

• Basic: int, float64, string, bool.
• Aggregate: array, struct.
• Reference: slice, map, channel, pointer, function.

What is the difference between an array and a slice?

An array has a fixed length set at compile time. A slice is a dynamic structure that references an underlying array.

// Arrayvar arr [3]int = [3]int{1, 2, 3}arr[0] = 10 // Ok

// Sliceslc := []int{1, 2, 3}slc = append(slc, 4) // Length can grow

Stumper question: What happens to memory during append if the slice's capacity is exceeded? (Answer: Go allocates a new array twice as large and copies the data).

How is a map structured in Go?

A map is a hash table. The iteration order is not guaranteed. Reading a non-existent key returns the zero value (e.g., 0 for int).

m := make(map[string]int)m["key"] = 42value, ok := m["key"] // ok == true if the key exists

2. Concurrency: Goroutines, Channels, and Mutexes

This is the most important topic for Go. You won't pass the interview without it.

What is a goroutine and how is it different from an OS thread?

A goroutine is a lightweight thread managed by the Go runtime. A goroutine's stack starts at 2-4 KB (compared to 1 MB for an OS thread). Thousands of goroutines run on a few OS threads (M:N model).

How do channels work? Give an example of the worker pool pattern.

func worker(id int, jobs <-chan int, results chan<- int) {    for j := range jobs {        results <- j * 2    }}

func main() {    jobs := make(chan int, 100)    results := make(chan int, 100)

    // Start 3 workers    for w := 1; w <= 3; w++ {        go worker(w, jobs, results)    }

    // Send jobs    for j := 1; j <= 5; j++ {        jobs <- j    }    close(jobs)

    // Collect results    for r := 1; r <= 5; r++ {        <-results    }}

What is the difference between a buffered and an unbuffered channel?

• Unbuffered: The sender blocks until the receiver accepts the message. Synchronous communication.
• Buffered: The sender blocks only when the buffer is full. Asynchronous communication.

How to avoid a deadlock?

Use select with a timeout or default:

select {case msg := <-ch:    fmt.Println(msg)case <-time.After(1 * time.Second):    fmt.Println("timeout")}

3. Interfaces, Generics, and Error Handling

Go is not a pure OOP language, but interfaces play a key role here.

How does duck typing work in Go?

A type implicitly implements an interface if it has all the required methods. This allows for writing flexible code.

type Stringer interface {    String() string}

type User struct {    Name string}

func (u User) Str