Golang Interview Questions

Golang (Go) is a modern programming language developed by Google, known for its simplicity, performance, and built-in concurrency support. It is widely used in areas such as backend development, microservice architectures, database integrations, and high-performance applications.

In this guide, you'll find enriched explanations with sample questions, tips, and example code covering key areas such as: Golang interview questions, Golang backend interview questions, Golang concurrency interview questions, Golang microservices interview questions, Golang database integration interview questions, Golang performance optimization interview questions, and Golang error handling interview questions.

1. What Are the Fundamentals of Go?

Go is a statically typed, compiled, and high-performance language. It stands out with its simple syntax, fast compilation, and powerful concurrency model.

Why Golang?

• Static type checking: Detect errors at compile time
• Lightweight syntax: Easy to read and learn
• Garbage collection: Automatic memory management
• Goroutines & Channels: Built-in concurrency support
• Cross-platform binaries: Compile for multiple OS with a single command

Basic Go Program:

package main
import "fmt"

func main() {
fmt.Println("Hello Golang!")
}

2. What Are Goroutines and Channels?

Goroutines are lightweight threads in Go, started with the go keyword.
Channels are used to communicate between goroutines.

Example:

package main
import (
"fmt"
"time"
)

func write(msg string) {
for i := 0; i < 3; i++ {
  fmt.Println(msg)
  time.Sleep(time.Millisecond * 500)
}
}

func main() {
go write("Techcareer")
write("Golang")
}

Channel Example:

func sendMessage(ch chan string) {
ch <- "Hello Channel!"
}

func main() {
ch := make(chan string)
go sendMessage(ch)
fmt.Println(<-ch)
}

3. Error Handling in Go

Go doesn’t have exception handling; instead, it uses the error type.

Example:

import "errors"

func divide(a, b int) (int, error) {
if b == 0 {
  return 0, errors.New("cannot divide by zero")
}
return a / b, nil
}

Usage:

result, err := divide(10, 0)
if err != nil {
fmt.Println("Error:", err)
} else {
fmt.Println("Result:", result)
}

4. Database Integration

Go uses database/sql and driver packages to connect to databases.

PostgreSQL Example:

import (
"database/sql"
_ "github.com/lib/pq"
)

db, err := sql.Open("postgres", "user=foo dbname=bar sslmode=disable")

Querying Data:

rows, err := db.Query("SELECT id, name FROM users")

5. Performance Optimization Techniques

Go is inherently fast, but performance can be improved in large systems.

Tips:

• Avoid unnecessary goroutines
• Use pointers in structs to reduce copying
• Choose appropriate data structures (map, slice, array)
• Use pprof for profiling CPU and memory usage
• Use sync.Pool to reuse objects and reduce allocations

Example:

var pool = sync.Pool{
New: func() interface{} {
  return new(bytes.Buffer)
},
}
buf := pool.Get().(*bytes.Buffer)
defer pool.Put(buf)

6. Microservice Architecture with Go

Microservices are small, independent services with a specific function. Go’s speed and concurrency model make it ideal for microservices.

Best Practices:

• Use net/http or frameworks like gin-gonic
• Containerize with Docker and Kubernetes
• Use gRPC for efficient communication
• Simple REST Service Example (net/http):

import (
"fmt"
"net/http"
)

func handler(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, "Hello Microservice!")
}

func main() {
http.HandleFunc("/", handler)
http.ListenAndServe(":8080", nil)
}

7. Working with JSON

Go handles JSON using the encoding/json package.

Parsing JSON:

type User struct {
Name string `json:"name"`
Age  int    `json:"age"`
}

data := `{"name": "Ahmet", "age": 30}`
var u User
json.Unmarshal([]byte(data), &u)

8. Unit Testing and Benchmarking

Go includes built-in testing tools with the testing package.

Unit Test Example:

func Add(a, b int) int {
return a + b
}

func TestAdd(t *testing.T) {
result := Add(2, 3)
if result != 5 {
  t.Errorf("Expected 5, got %d", result)
}
}

Benchmark Example:

func BenchmarkAdd(b *testing.B) {
for i := 0; i < b.N; i++ {
  Add(2, 3)
}
}

9. Common Go Interview Questions

• What is a pointer in Go?
  A pointer stores the memory address of a variable.
   
• What does defer do?
  Executes a function after the surrounding function completes (e.g., closing files).
   
• Difference between channel and buffered channel?
  Buffered channels store data up to a limit. Unbuffered channels block until received.
   
• What is an interface in Go?
  A contract that defines behavior. Allows multiple types to implement shared logic.
   
• What is a struct and why use it?
  A struct defines data models, commonly used for JSON handling and DTOs.

10. Tips & Best Practices

• Use go fmt to auto-format your code.
• Always check if err != nil after operations.
• Use modular architecture in large projects.
• Use the context package to control HTTP requests.
• Use tools like go vet, golint, and staticcheck for code analysis.

Golang is a powerful choice for both beginner and advanced developers in terms of performance and maintainability. In this article, we provided detailed insights and examples on Golang interview questions, Golang concurrency, database integration, microservices, and error handling.

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