Go Backend Development
A comprehensive skill for building production-grade backend systems with Go. Master goroutines, channels, web servers, database integration, microservices architecture, and deployment patterns for scalable, concurrent backend applications.
When to Use This Skill
Use this skill when:
- Building high-performance web servers and REST APIs
- Developing microservices architectures with gRPC or HTTP
- Implementing concurrent processing with goroutines and channels
- Creating real-time systems requiring high throughput
- Building database-backed applications with connection pooling
- Developing cloud-native applications for containerized deployment
- Writing performance-critical backend services
- Building distributed systems with service discovery
- Implementing event-driven architectures
- Creating CLI tools and system utilities with networking capabilities
- Developing WebSocket servers for real-time communication
- Building data processing pipelines with concurrent workers
Go excels at:
- Network programming and HTTP services
- Concurrent processing with lightweight goroutines
- System-level programming with garbage collection
- Cross-platform compilation
- Fast compilation times for rapid development
- Built-in testing and benchmarking
Core Concepts
1. Goroutines: Lightweight Concurrency
Goroutines are lightweight threads managed by the Go runtime. They enable concurrent execution with minimal overhead.
Key Characteristics:
- Extremely lightweight (start with ~2KB stack)
- Multiplexed onto OS threads by the runtime
- Thousands or millions can run concurrently
- Scheduled cooperatively with integrated scheduler
Basic Goroutine Pattern:
func main() {
// Launch concurrent computation
go expensiveComputation(x, y, z)
anotherExpensiveComputation(a, b, c)
}The go keyword launches a new goroutine, allowing expensiveComputation to run concurrently with anotherExpensiveComputation. This is fundamental to Go's concurrency model.
Common Use Cases:
- Background processing
- Concurrent API calls
- Parallel data processing
- Real-time event handling
- Connection handling in servers
2. Channels: Safe Communication
Channels provide type-safe communication between goroutines, eliminating the need for explicit locks in many scenarios.
Channel Types:
// Unbuffered channel - synchronous communication
ch := make(chan int)
// Buffered channel - asynchronous up to buffer size
ch := make(chan int, 100)
// Read-only channel
func receive(ch <-chan int) { /* ... */ }
// Write-only channel
func send(ch chan<- int) { /* ... */ }Synchronization with Channels:
func computeAndSend(ch chan int, x, y, z int) {
ch <- expensiveComputation(x, y, z)
}
func main() {
ch := make(chan int)
go computeAndSend(ch, x, y, z)
v2 := anotherExpensiveComputation(a, b, c)
v1 := <-ch // Block until result available
fmt.Println(v1, v2)
}This pattern ensures both computations complete before proceeding, with the channel providing both communication and synchronization.
Channel Patterns:
- Producer-consumer
- Fan-out/fan-in
- Pipeline stages
- Timeouts and cancellation
- Semaphores and rate limiting
3. Select Statement: Multiplexing Channels
The select statement enables multiplexing multiple channel operations, similar to a switch for channels.
Timeout Implementation:
timeout := make(chan bool, 1)
go func() {
time.Sleep(1 * time.Second)
timeout <- true
}()
select {
case <-ch:
// Read from ch succeeded
case <-timeout:
// Operation timed out
}Context-Based Cancellation:
select {
case result := <-resultCh:
return result
case <-ctx.Done():
return ctx.Err()
}4. Context Package: Request-Scoped Values
The context.Context interface manages deadlines, cancellation signals, and request-scoped values across API boundaries.
Context Interface:
type Context interface {
// Done returns a channel closed when work should be canceled
Done() <-chan struct{}
// Err returns why context was canceled
Err() error
// Deadline returns when work should be canceled
Deadline() (deadline time.Time, ok bool)
// Value returns request-scoped value
Value(key any) any
}Creating Contexts:
// Background context - never canceled
ctx := context.Background()
// With cancellation
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
// With timeout
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
// With deadline
deadline := time.Now().Add(10 * time.Second)
ctx, cancel := context.WithDeadline(context.Background(), deadline)
defer cancel()
// With values
ctx = context.WithValue(parentCtx, key, value)Best Practices:
- Always pass context as first parameter:
func DoSomething(ctx context.Context,...) - Call
defer cancel()immediately after creating cancelable context - Propagate context through call chain
- Check
ctx.Done()in long-running operations - Use context values only for request-scoped data, not optional parameters
5. WaitGroup: Coordinating Goroutines
sync.WaitGroup waits for a collection of goroutines to finish.
Basic Pattern:
var wg sync.WaitGroup
for i := 0; i < 10; i++ {
wg.Add(1)
go func(id int) {
defer wg.Done()
// Do work
}(i)
}
wg.Wait() // Block until all goroutines completeCommon Use Cases:
- Waiting for parallel tasks
- Coordinating worker pools
- Ensuring cleanup completion
- Synchronizing shutdown
6. Mutex: Protecting Shared State
When shared state is necessary, use sync.Mutex or sync.RWMutex for protection.
Mutex Pattern:
var (
service map[string]net.Addr
serviceMu sync.Mutex
)
func RegisterService(name string, addr net.Addr) {
serviceMu.Lock()
defer serviceMu.Unlock()
service[name] = addr
}
func LookupService(name string) net.Addr {
serviceMu.Lock()
defer serviceMu.Unlock()
return service[name]
}RWMutex for Read-Heavy Workloads:
var (
cache map[string]interface{}
cacheMu sync.RWMutex
)
func Get(key string) interface{} {
cacheMu.RLock()
defer cacheMu.RUnlock()
return cache[key]
}
func Set(key string, value interface{}) {
cacheMu.Lock()
defer cacheMu.Unlock()
cache[key] = value
}7. Concurrent Web Server Pattern
Go's standard pattern for handling concurrent connections:
for {
rw := l.Accept()
conn := newConn(rw, handler)
go conn.serve() // Handle each connection concurrently
}Each accepted connection is handled in its own goroutine, allowing the server to scale to thousands of concurrent connections efficiently.
Web Server Development
HTTP Server Basics
Simple HTTP Server:
package main
import (
"fmt"
"net/http"
)
func main() {
http.HandleFunc("/", handler)
http.ListenAndServe("localhost:8080", nil)
}
func handler(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, "Hello!")
}Request Handling Patterns
Handler Functions:
func handler(w http.ResponseWriter, r *http.Request) {
// Read request
method := r.Method
path := r.URL.Path
query := r.URL.Query()
// Write response
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(http.StatusOK)
fmt.Fprintf(w, `{"message": "success"}`)
}Handler Structs:
type APIHandler struct {
db *sql.DB
logger *log.Logger
}
func (h *APIHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// Access dependencies
h.logger.Printf("Request: %s %s", r.Method, r.URL.Path)
// Handle request
}Middleware Pattern
Logging Middleware:
func loggingMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
start := time.Now()
next.ServeHTTP(w, r)
log.Printf("%s %s %v", r.Method, r.URL.Path, time.Since(start))
})
}
// Usage
http.Handle("/api/", loggingMiddleware(apiHandler))Authentication Middleware:
func authMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
token := r.Header.Get("Authorization")
if !isValidToken(token) {
http.Error(w, "Unauthorized", http.StatusUnauthorized)
return
}
next.ServeHTTP(w, r)
})
}Chaining Middleware:
handler := loggingMiddleware(authMiddleware(corsMiddleware(apiHandler)))
http.Handle("/api/", handler)Context in HTTP Handlers
HTTP Request with Context:
func handleSearch(w http.ResponseWriter, req *http.Request) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
// Check query parameter
query := req.FormValue("q")
if query == "" {
http.Error(w, "missing query", http.StatusBadRequest)
return
}
// Perform search with context
results, err := performSearch(ctx, query)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
// Render results
renderTemplate(w, results)
}Context-Aware HTTP Request:
func httpDo(ctx context.Context, req *http.Request,
f func(*http.Response, error) error) error {
c := &http.Client{}
// Run request in goroutine
ch := make(chan error, 1)
go func() {
ch <- f(c.Do(req))
}()
// Wait for completion or cancellation
select {
case <-ctx.Done():
<-ch // Wait for f to return
return ctx.Err()
case err := <-ch:
return err
}
}Routing Patterns
Custom Router:
type Router struct {
routes map[string]http.HandlerFunc
}
func (r *Router) Handle(pattern string, handler http.HandlerFunc) {
r.routes[pattern] = handler
}
func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
if handler, ok := r.routes[req.URL.Path]; ok {
handler(w, req)
} else {
http.NotFound(w, req)
}
}RESTful API Structure:
// GET /api/users
func listUsers(w http.ResponseWriter, r *http.Request) { /* ... */ }
// GET /api/users/:id
func getUser(w http.ResponseWriter, r *http.Request) { /* ... */ }
// POST /api/users
func createUser(w http.ResponseWriter, r *http.Request) { /* ... */ }
// PUT /api/users/:id
func updateUser(w http.ResponseWriter, r *http.Request) { /* ... */ }
// DELETE /api/users/:id
func deleteUser(w http.ResponseWriter, r *http.Request) { /* ... */ }Concurrency Patterns
1. Pipeline Pattern
Pipelines process data through multiple stages connected by channels.
Generator Stage:
func gen(nums ...int) <-chan int {
out := make(chan int)
go func() {
for _, n := range nums {
out <- n
}
close(out)
}()
return out
}Processing Stage:
func sq(in <-chan int) <-chan int {
out := make(chan int)
go func() {
for n := range in {
out <- n * n
}
close(out)
}()
return out
}Pipeline Usage:
func main() {
// Set up pipeline
c := gen(2, 3)
out := sq(c)
// Consume output
for n := range out {
fmt.Println(n) // 4 then 9
}
}Buffered Generator (No Goroutine Needed):
func gen(nums ...int) <-chan int {
out := make(chan int, len(nums))
for _, n := range nums {
out <- n
}
close(out)
return out
}2. Fan-Out/Fan-In Pattern
Distribute work across multiple workers and merge results.
Fan-Out: Multiple Workers:
func main() {
in := gen(2, 3, 4, 5)
// Fan out: distribute work across two goroutines
c1 := sq(in)
c2 := sq(in)
// Fan in: merge results
for n := range merge(c1, c2) {
fmt.Println(n)
}
}Merge Function (Fan-In):
func merge(cs ...<-chan int) <-chan int {
var wg sync.WaitGroup
out := make(chan int)
// Start output goroutine for each input channel
output := func(c <-chan int) {
for n := range c {
out <- n
}
wg.Done()
}
wg.Add(len(cs))
for _, c := range cs {
go output(c)
}
// Close out once all outputs are done
go func() {
wg.Wait()
close(out)
}()
return out
}3. Explicit Cancellation Pattern
Cancellation with Done Channel:
func sq(done <-chan struct{}, in <-chan int) <-chan int {
out := make(chan int)
go func() {
defer close(out)
for n := range in {
select {
case out <- n * n:
case <-done:
return
}
}
}()
return out
}Broadcasting Cancellation:
func main() {
done := make(chan struct{})
defer close(done) // Broadcast to all goroutines
in := gen(done, 2, 3, 4)
c1 := sq(done, in)
c2 := sq(done, in)
// Process subset of results
out := merge(done, c1, c2)
fmt.Println(<-out)
// done closed on return, canceling all pipeline stages
}Merge with Cancellation:
func merge(done <-chan struct{}, cs ...<-chan int) <-chan int {
var wg sync.WaitGroup
out := make(chan int)
output := func(c <-chan int) {
defer wg.Done()
for n := range c {
select {
case out <- n:
case <-done:
return
}
}
}
wg.Add(len(cs))
for _, c := range cs {
go output(c)
}
go func() {
wg.Wait()
close(out)
}()
return out
}4. Worker Pool Pattern
Fixed Number of Workers:
func handle(queue chan *Request) {
for r := range queue {
process(r)
}
}
func Serve(clientRequests chan *Request, quit chan bool) {
// Start handlers
for i := 0; i < MaxOutstanding; i++ {
go handle(clientRequests)
}
<-quit // Wait to exit
}Semaphore Pattern:
var sem = make(chan int, MaxOutstanding)
func handle(r *Request) {
sem <- 1 // Acquire
process(r)
<-sem // Release
}
func Serve(queue chan *Request) {
for req := range queue {
go handle(req)
}
}Limiting Goroutine Creation:
func Serve(queue chan *Request) {
for req := range queue {
sem <- 1 // Acquire before creating goroutine
go func() {
process(req)
<-sem // Release
}()
}
}5. Query Racing Pattern
Query multiple sources and return first result:
func Query(conns []Conn, query string) Result {
ch := make(chan Result)
for _, conn := range conns {
go func(c Conn) {
select {
case ch <- c.DoQuery(query):
default:
}
}(conn)
}
return <-ch
}6. Parallel Processing Example
Serial MD5 Calculation:
func MD5All(root string) (map[string][md5.Size]byte, error) {
m := make(map[string][md5.Size]byte)
err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
if !info.Mode().IsRegular() {
return nil
}
data, err := ioutil.ReadFile(path)
if err != nil {
return err
}
m[path] = md5.Sum(data)
return nil
})
return m, err
}Parallel MD5 with Pipeline:
type result struct {
path string
sum [md5.Size]byte
err error
}
func sumFiles(done <-chan struct{}, root string) (<-chan result, <-chan error) {
c := make(chan result)
errc := make(chan error, 1)
go func() {
defer close(c)
err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
if !info.Mode().IsRegular() {
return nil
}
// Start goroutine for each file
go func() {
data, err := ioutil.ReadFile(path)
select {
case c <- result{path, md5.Sum(data), err}:
case <-done:
}
}()
// Check for early cancellation
select {
case <-done:
return errors.New("walk canceled")
default:
return nil
}
})
select {
case errc <- err:
case <-done:
}
}()
return c, errc
}
func MD5All(root string) (map[string][md5.Size]byte, error) {
done := make(chan struct{})
defer close(done)
c, errc := sumFiles(done, root)
m := make(map[string][md5.Size]byte)
for r := range c {
if r.err != nil {
return nil, r.err
}
m[r.path] = r.sum
}
if err := <-errc; err != nil {
return nil, err
}
return m, nil
}7. Leaky Buffer Pattern
Efficient buffer reuse:
var freeList = make(chan *Buffer, 100)
func server() {
for {
b := <-serverChan // Wait for work
process(b)
// Try to reuse buffer
select {
case freeList <- b:
// Buffer on free list
default:
// Free list full, GC will reclaim
}
}
}Database Integration
Connection Management
Database Connection Pool:
import "database/sql"
func initDB(dataSourceName string) (*sql.DB, error) {
db, err := sql.Open("postgres", dataSourceName)
if err != nil {
return nil, err
}
// Configure connection pool
db.SetMaxOpenConns(25)
db.SetMaxIdleConns(5)
db.SetConnMaxLifetime(5 * time.Minute)
db.SetConnMaxIdleTime(10 * time.Minute)
// Verify connection
if err := db.Ping(); err != nil {
return nil, err
}
return db, nil
}Query Patterns
Single Row Query:
func getUser(db *sql.DB, userID int) (*User, error) {
user := &User{}
err := db.QueryRow(
"SELECT id, name, email FROM users WHERE id = $1",
userID,
).Scan(&user.ID, &user.Name, &user.Email)
if err == sql.ErrNoRows {
return nil, fmt.Errorf("user not found")
}
if err != nil {
return nil, err
}
return user, nil
}Multiple Row Query:
func listUsers(db *sql.DB) ([]*User, error) {
rows, err := db.Query("SELECT id, name, email FROM users")
if err != nil {
return nil, err
}
defer rows.Close()
var users []*User
for rows.Next() {
user := &User{}
if err := rows.Scan(&user.ID, &user.Name, &user.Email); err != nil {
return nil, err
}
users = append(users, user)
}
if err := rows.Err(); err != nil {
return nil, err
}
return users, nil
}Insert/Update with Context:
func createUser(ctx context.Context, db *sql.DB, user *User) error {
query := "INSERT INTO users (name, email) VALUES ($1, $2) RETURNING id"
err := db.QueryRowContext(ctx, query, user.Name, user.Email).Scan(&user.ID)
return err
}Transaction Handling
func transferFunds(ctx context.Context, db *sql.DB, from, to int, amount decimal.Decimal) error {
tx, err := db.BeginTx(ctx, nil)
if err != nil {
return err
}
defer tx.Rollback() // Rollback if not committed
// Debit from account
_, err = tx.ExecContext(ctx,
"UPDATE accounts SET balance = balance - $1 WHERE id = $2",
amount, from)
if err != nil {
return err
}
// Credit to account
_, err = tx.ExecContext(ctx,
"UPDATE accounts SET balance = balance + $1 WHERE id = $2",
amount, to)
if err != nil {
return err
}
return tx.Commit()
}Prepared Statements
func insertUsers(db *sql.DB, users []*User) error {
stmt, err := db.Prepare("INSERT INTO users (name, email) VALUES ($1, $2)")
if err != nil {
return err
}
defer stmt.Close()
for _, user := range users {
_, err := stmt.Exec(user.Name, user.Email)
if err != nil {
return err
}
}
return nil
}Error Handling
Custom Error Types
type ValidationError struct {
Field string
Message string
}
func (e *ValidationError) Error() string {
return fmt.Sprintf("%s: %s", e.Field, e.Message)
}
// Usage
if email == "" {
return &ValidationError{Field: "email", Message: "required"}
}Error Wrapping
import "fmt"
func processData(data []byte) error {
err := validateData(data)
if err != nil {
return fmt.Errorf("process data: %w", err)
}
return nil
}
// Unwrapping
if errors.Is(err, ErrValidation) {
// Handle validation error
}
if errors.As(err, &validationErr) {
// Access ValidationError fields
}Sentinel Errors
var (
ErrNotFound = errors.New("not found")
ErrUnauthorized = errors.New("unauthorized")
ErrInvalidInput = errors.New("invalid input")
)
// Usage
if errors.Is(err, ErrNotFound) {
http.Error(w, "Resource not found", http.StatusNotFound)
}Testing
Unit Tests
func TestGetUser(t *testing.T) {
db := setupTestDB(t)
defer db.Close()
user, err := getUser(db, 1)
if err != nil {
t.Fatalf("getUser failed: %v", err)
}
if user.Name != "John Doe" {
t.Errorf("expected name John Doe, got %s", user.Name)
}
}Table-Driven Tests
func TestValidateEmail(t *testing.T) {
tests := []struct {
name string
email string
wantErr bool
}{
{"valid email", "user@example.com", false},
{"missing @", "userexample.com", true},
{"empty string", "", true},
{"missing domain", "user@", true},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
err := validateEmail(tt.email)
if (err != nil) != tt.wantErr {
t.Errorf("validateEmail(%q) error = %v, wantErr %v",
tt.email, err, tt.wantErr)
}
})
}
}Benchmarks
func BenchmarkConcurrentMap(b *testing.B) {
m := make(map[string]int)
var mu sync.Mutex
b.RunParallel(func(pb *testing.PB) {
for pb.Next() {
mu.Lock()
m["key"]++
mu.Unlock()
}
})
}HTTP Handler Testing
func TestHandler(t *testing.T) {
req := httptest.NewRequest("GET", "/api/users", nil)
w := httptest.NewRecorder()
handler(w, req)
resp := w.Result()
if resp.StatusCode != http.StatusOK {
t.Errorf("expected status 200, got %d", resp.StatusCode)
}
body, _ := ioutil.ReadAll(resp.Body)
// Assert body content
}Production Patterns
Graceful Shutdown
func main() {
srv := &http.Server{
Addr: ":8080",
Handler: router,
}
// Start server in goroutine
go func() {
if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
log.Fatalf("listen: %s\n", err)
}
}()
// Wait for interrupt signal
quit := make(chan os.Signal, 1)
signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
<-quit
log.Println("Shutting down server...")
// Graceful shutdown with timeout
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
defer cancel()
if err := srv.Shutdown(ctx); err != nil {
log.Fatal("Server forced to shutdown:", err)
}
log.Println("Server exited")
}Configuration Management
type Config struct {
ServerPort int `env:"PORT" envDefault:"8080"`
DBHost string `env:"DB_HOST" envDefault:"localhost"`
DBPort int `env:"DB_PORT" envDefault:"5432"`
LogLevel string `env:"LOG_LEVEL" envDefault:"info"`
Timeout time.Duration `env:"TIMEOUT" envDefault:"30s"`
}
func loadConfig() (*Config, error) {
cfg := &Config{}
if err := env.Parse(cfg); err != nil {
return nil, err
}
return cfg, nil
}Structured Logging
import "log/slog"
func setupLogger() *slog.Logger {
return slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
Level: slog.LevelInfo,
}))
}
func handler(w http.ResponseWriter, r *http.Request) {
logger := slog.With(
"method", r.Method,
"path", r.URL.Path,
"remote", r.RemoteAddr,
)
logger.Info("handling request")
// Process request
logger.Info("request completed", "status", 200)
}Health Checks
func healthHandler(db *sql.DB) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
// Check database
if err := db.Ping(); err != nil {
w.WriteHeader(http.StatusServiceUnavailable)
json.NewEncoder(w).Encode(map[string]string{
"status": "unhealthy",
"error": err.Error(),
})
return
}
// Check other dependencies...
w.WriteHeader(http.StatusOK)
json.NewEncoder(w).Encode(map[string]string{
"status": "healthy",
})
}
}Rate Limiting
import "golang.org/x/time/rate"
func rateLimitMiddleware(limiter *rate.Limiter) func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if !limiter.Allow() {
http.Error(w, "Too Many Requests", http.StatusTooManyRequests)
return
}
next.ServeHTTP(w, r)
})
}
}
// Usage
limiter := rate.NewLimiter(rate.Limit(10), 20) // 10 req/sec, burst 20
handler := rateLimitMiddleware(limiter)(apiHandler)Panic Recovery
func safelyDo(work *Work) {
defer func() {
if err := recover(); err != nil {
log.Println("work failed:", err)
}
}()
do(work)
}
func server(workChan <-chan *Work) {
for work := range workChan {
go safelyDo(work)
}
}Microservices Patterns
Service Structure
type UserService struct {
db *sql.DB
cache *redis.Client
logger *slog.Logger
}
func NewUserService(db *sql.DB, cache *redis.Client, logger *slog.Logger) *UserService {
return &UserService{
db: db,
cache: cache,
logger: logger,
}
}
func (s *UserService) GetUser(ctx context.Context, userID string) (*User, error) {
// Check cache first
if user, err := s.getFromCache(ctx, userID); err == nil {
return user, nil
}
// Query database
user, err := s.getFromDB(ctx, userID)
if err != nil {
return nil, err
}
// Update cache
go s.updateCache(context.Background(), user)
return user, nil
}gRPC Service
type server struct {
pb.UnimplementedUserServiceServer
db *sql.DB
}
func (s *server) GetUser(ctx context.Context, req *pb.GetUserRequest) (*pb.User, error) {
user := &pb.User{}
err := s.db.QueryRowContext(ctx,
"SELECT id, name, email FROM users WHERE id = $1",
req.GetId(),
).Scan(&user.Id, &user.Name, &user.Email)
if err != nil {
return nil, status.Errorf(codes.NotFound, "user not found")
}
return user, nil
}Service Discovery
type ServiceRegistry struct {
services map[string][]string
mu sync.RWMutex
}
func (r *ServiceRegistry) Register(name, addr string) {
r.mu.Lock()
defer r.mu.Unlock()
r.services[name] = append(r.services[name], addr)
}
func (r *ServiceRegistry) Discover(name string) (string, error) {
r.mu.RLock()
defer r.mu.RUnlock()
addrs := r.services[name]
if len(addrs) == 0 {
return "", fmt.Errorf("service %s not found", name)
}
// Simple round-robin
return addrs[rand.Intn(len(addrs))], nil
}Circuit Breaker
type CircuitBreaker struct {
maxFailures int
timeout time.Duration
failures int
lastFailure time.Time
state string // closed, open, half-open
mu sync.Mutex
}
func (cb *CircuitBreaker) Call(fn func() error) error {
cb.mu.Lock()
if cb.state == "open" {
if time.Since(cb.lastFailure) > cb.timeout {
cb.state = "half-open"
} else {
cb.mu.Unlock()
return errors.New("circuit breaker open")
}
}
cb.mu.Unlock()
err := fn()
cb.mu.Lock()
defer cb.mu.Unlock()
if err != nil {
cb.failures++
cb.lastFailure = time.Now()
if cb.failures >= cb.maxFailures {
cb.state = "open"
}
return err
}
cb.failures = 0
cb.state = "closed"
return nil
}Best Practices
1. Goroutine Management
- Always consider goroutine lifecycle and cleanup
- Use contexts for cancellation propagation
- Avoid goroutine leaks by ensuring all goroutines can exit
- Be cautious with closures in loops - pass values explicitly
Anti-pattern:
for _, v := range values {
go func() {
fmt.Println(v) // All goroutines share same v
}()
}Correct:
for _, v := range values {
go func(val string) {
fmt.Println(val) // Each goroutine gets its own copy
}(v)
}2. Channel Best Practices
- Close channels from sender, not receiver
- Use buffered channels to prevent goroutine leaks
- Consider using
selectwithdefaultfor non-blocking operations - Remember: sending on closed channel panics, receiving returns zero value
3. Error Handling
- Return errors, don't panic (except for truly exceptional cases)
- Wrap errors with context using
fmt.Errorf("%w", err) - Use custom error types for programmatic handling
- Log errors with sufficient context
4. Performance
- Use
sync.Poolfor frequently allocated objects - Profile before optimizing:
go test -bench. -cpuprofile=cpu.prof - Consider
sync.Mapfor concurrent map access patterns - Use buffered channels for known capacity
- Avoid unnecessary allocations in hot paths
5. Code Organization
project/
├── cmd/
│ └── server/
│ └── main.go # Application entry point
├── internal/
│ ├── api/ # HTTP handlers
│ ├── service/ # Business logic
│ ├── repository/ # Data access
│ └── middleware/ # HTTP middleware
├── pkg/
│ └── utils/ # Public utilities
├── migrations/ # Database migrations
├── config/ # Configuration files
└── docker/ # Docker files6. Security
- Validate all inputs
- Use prepared statements for SQL queries
- Implement rate limiting
- Use HTTPS in production
- Sanitize error messages sent to clients
- Use context timeouts to prevent resource exhaustion
- Implement proper authentication and authorization
7. Testing
- Write table-driven tests
- Use
t.Helper()for test helper functions - Mock external dependencies
- Use
httptestfor HTTP handler testing - Write benchmarks for performance-critical code
- Aim for >80% test coverage on business logic
Common Pitfalls
1. Race Conditions
Problem:
var service map[string]net.Addr
func RegisterService(name string, addr net.Addr) {
service[name] = addr // RACE CONDITION
}
func LookupService(name string) net.Addr {
return service[name] // RACE CONDITION
}Solution:
var (
service map[string]net.Addr
serviceMu sync.Mutex
)
func RegisterService(name string, addr net.Addr) {
serviceMu.Lock()
defer serviceMu.Unlock()
service[name] = addr
}2. Goroutine Leaks
Problem:
func process() {
ch := make(chan int)
go func() {
ch <- expensive() // Blocks forever if no receiver
}()
// Returns without reading from ch
}Solution:
func process() {
ch := make(chan int, 1) // Buffered channel
go func() {
ch <- expensive() // Won't block
}()
}3. Not Closing Channels
Receivers need to know when no more values are coming:
func gen(nums ...int) <-chan int {
out := make(chan int)
go func() {
for _, n := range nums {
out <- n
}
close(out) // IMPORTANT: close when done
}()
return out
}4. Blocking on Unbuffered Channels
// This will deadlock
ch := make(chan int)
ch <- 1 // Blocks forever - no receiver
v := <-chUse buffered channels or separate goroutines.
5. Unsynchronized Channel Operations
c := make(chan struct{})
// RACE CONDITION
go func() { c <- struct{}{} }()
close(c)Ensure happens-before relationship with proper synchronization.
Resources and References
Official Documentation
- Go Documentation: https://go.dev/doc/
- Effective Go: https://go.dev/doc/effective_go
- Go Blog: https://go.dev/blog/
- Go by Example: https://gobyexample.com/
Concurrency Resources
- Go Concurrency Patterns: https://go.dev/blog/pipelines
- Context Package: https://go.dev/blog/context
- Share Memory By Communicating: https://go.dev/blog/codelab-share
Standard Library
- net/http: https://pkg.go.dev/net/http
- database/sql: https://pkg.go.dev/database/sql
- context: https://pkg.go.dev/context
- sync: https://pkg.go.dev/sync
Tools
- Race Detector:
go test -race - Profiler:
go tool pprof - Benchmarking:
go test -bench - Static Analysis:
go vet,staticcheck
Skill Version: 1.0.0 Last Updated: October 2025 Skill Category: Backend Development, Systems Programming, Concurrent Programming Prerequisites: Basic programming knowledge, understanding of HTTP, familiarity with command line Recommended Next Skills: docker-deployment, kubernetes-orchestration, grpc-microservices