🐹 Go (Golang) Backend Engineering Masterclass

High-Performance Backend Engineering, CSP Concurrency (Goroutines & Channels), Memory Primitives, Structs & Implicit Interfaces, Error Handling Idioms aur Scalable Microservices Architecture.

Curriculum Index

1. Module 1: The Go Philosophy, Type System & Memory Layout
2. Module 2: Pointers, Structs & Implicit Interfaces
3. Module 3: Idiomatic Error Handling vs Exceptions
4. Module 4: Concurrency with Goroutines, WaitGroups & Mutexes
5. Module 5: CSP Pattern: Buffered & Unbuffered Channels with Select
6. Module 6: Building Production HTTP REST APIs with Standard Library
7. Module 7: Context Package, Cancellation & SQL Connection Pools

Module 01

1️⃣ The Go Philosophy, Type System & Memory Layout

Definition: Go (Golang) Google dwara design ki gayi ek statically-typed, compiled programming language hai jo simple syntax, ultra-fast compilation, native multicore concurrency aur direct OS machine binary generation deliver karti hai.

Criteria	Go (Golang)	Java / Node.js
Execution Model	Direct machine code binary compilation. Zero runtime VM overhead.	JVM Bytecode JIT execution (Java) / V8 dynamic JIT runtime (Node).
Concurrency Cost	~2 KB initial stack size per Goroutine. Millions spawn ho sakte hain.	~1 MB stack size per OS Thread (Java). Single-threaded event loop (Node).
Type Inheritance	Zero class inheritance. Composition via embedded structs & interfaces.	Classical class-based deep inheritance hierarchies.

Module 02

2️⃣ Pointers, Structs & Implicit Interfaces

Go me interfaces implicitly satisfy hote hain. Kisi class ko implements keyword likhne ki zaroorat nahi hoti:

package main

import "fmt"

// 1. Interface Declaration
type Notifier interface {
    Send(message string) error
}

// 2. Concrete Struct
type EmailSender struct {
    EmailAddress string
}

// 3. Method Implementation (Implicitly satisfies Notifier!)
func (e EmailSender) Send(message string) error {
    fmt.Printf("Dispatching email to %s: %s\n", e.EmailAddress, message)
    return nil
}

func NotifyUser(n Notifier, msg string) {
    n.Send(msg)
}

Module 03

3️⃣ Idiomatic Error Handling vs Exceptions

Go me try-catch blocks exist nahi karte. Errors standard values hote hain jo multiple return values ke sath propagate kiye jaate hain:

import (
    "errors"
    "fmt"
)

var ErrInvalidSalary = errors.New("salary must be greater than zero")

func CalculateAnnualPackage(monthlySalary float64) (float64, error) {
    if monthlySalary <= 0 {
        return 0, ErrInvalidSalary
    }
    return monthlySalary * 12, nil
}

// Standard Invocation Idiom:
pkg, err := CalculateAnnualPackage(85000)
if err != nil {
    // Handle error explicitly
    fmt.Printf("Failed: %v\n", err)
    return
}
fmt.Printf("Total CTC: ₹%.2f\n", pkg)

Module 04

4️⃣ Concurrency: Goroutines, WaitGroups & Mutexes

Goroutine ko spawn karne ke liye sirf go keyword lagana hota hai. Shared state race conditions ko prevent karne ke liye sync.Mutex ya sync.WaitGroup use kiya jata hai:

package main

import (
    "sync"
)

type SafeCounter struct {
    mu    sync.Mutex
    count int
}

func (c *SafeCounter) Increment(wg *sync.WaitGroup) {
    defer wg.Done()
    c.mu.Lock()         // Acquire Lock
    c.count++
    c.mu.Unlock()       // Release Lock
}

Live Go M:N Scheduler & Channel Pipeline Simulator

[Go Concurrency Runtime]: Scheduler Ready. GOMAXPROCS = 8 Logical CPUs. Select a concurrency pattern above...

Module 05

5️⃣ CSP Pattern: Channels & Non-Blocking Select

"Do not communicate by sharing memory; instead, share memory by communicating."

Channel Type	Declaration	Blocking Behavior
Unbuffered	ch := make(chan int)	Sender tab tak block rehta hai jab tak receiver data accept na kare (Synchronous handshake).
Buffered	ch := make(chan int, 5)	Sender tab tak non-blocking rehta hai jab tak buffer capacity (5) full na ho jaye.

// Multiplexing Channels with select
select {
case msg := <-jobQueue:
    fmt.Println("Processed job:", msg)
case <-time.After(2 * time.Second):
    fmt.Println("Worker timeout reached! Moving on.")
}

Module 06

6️⃣ Production REST API with net/http

package main

import (
    "encoding/json"
    "net/http"
)

type JobResponse struct {
    ID    string `json:"id"`
    Title string `json:"title"`
}

func jobsHandler(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    
    response := JobResponse{ID: "JOB-401", Title: "Senior Golang Backend Lead"}
    json.NewEncoder(w).Encode(response)
}

func main() {
    mux := http.NewServeMux()
    mux.HandleFunc("GET /api/v1/jobs", jobsHandler)
    http.ListenAndServe(":8080", mux)
}

Module 07

7️⃣ Context Package & Database Connection Pooling

Production Database Pool Configurations (database/sql):
• db.SetMaxOpenConns(25): Database server par CPU saturation rokne ke liye hard limit.
• db.SetMaxIdleConns(25): Reusable idle connections pool me maintain rakhna.
• db.SetConnMaxLifetime(5 * time.Minute): AWS/Cloud firewalls dwara stale TCP connections terminate hone se rokna.
• context.WithTimeout(ctx, 2*time.Second): Slow queries ko background me safely kill karna.