Go Concurrency Explained 😎

Idiomatic Code, Shared Channels aur Done Signals ka Full Scene

🧠 Goroutine kya hota hai?

Simple bhai —

Goroutine ek lightweight thread hai jo Go runtime khud manage karta hai.

OS thread nahi hota — Go ka runtime apne M:N scheduler se M goroutines ko N OS threads pe efficiently map karta hai (M » N, aur N typically CPU cores ke barabar hota hai).

Aur channel? Ek safe line hai jahan se goroutines baat karte hain — bina lock ke.

c := make(chan int)
go func() { c <- 42 }()
fmt.Println(<-c)

Bas — ek ne bheja, doosre ne liya. No tension.

⚙️ “Idiomatic Go” ka matlab kya hota hai?

“Idiomatic” matlab Go ka natural tareeka likhne ka.
Aise likho jaise Go khud keh raha ho — “haan bhai, ab sahi likha.”

Idiomatic code = Simple + Safe + Predictable ✅

🚦 Unbuffered Channel ka Scene

c := make(chan int)

go func() {
	fmt.Println("sending...")
	c <- 99
	fmt.Println("sent!")
}()

time.Sleep(1 * time.Second)
fmt.Println(<-c)

Output:

sending...
sent!
99

Yaani sender tab tak rukta hai jab tak receiver ready nahi — perfect synchronization point 💪

💣 Shared Channel Fatega Agar Galat Close Kiya

Agar 2-3 goroutine ek hi channel pe likh rahe hain aur koi ek ne close kar diya —
💥 Boom! panic: send on closed channel

✅ Solution — Ek Banda Close Karega

var wg sync.WaitGroup
c := make(chan int)

for i := 0; i < 3; i++ {
	wg.Add(1)
	go func(id int) {
		defer wg.Done()
		c <- id
	}(i)
}

go func() {
	wg.Wait()
	close(c) // ek hi banda close karega
}()

for v := range c {
	fmt.Println(v)
}

Idhar sab chill hai — koi panic nahi, koi leak nahi 🔥

🧘 Early Stop with done

Jab pehla hi mismatch mil gaya, toh baaki goroutines ko politely bol do — “bhai ruk jao.”

done := make(chan struct{})

select {
case ch <- value:
case <-done:
	return // respectful exit
}

close(done) sab goroutines ko ek saath unblock kar deta hai — ekdum clean exit.

⚡ Flow Samjho (Diagram)

flowchart LR
    A[Main] -->|go| B[Walk Goroutine 1]
    A -->|go| C[Walk Goroutine 2]
    B -->|values| D[(Channel)]
    C -->|values| D
    A -->|compare| D
    A -->|mismatch| E[close(done)]
    B -->|<-done| F[exit]
    C -->|<-done| G[exit]

🔑 Bhai’s Takeaways

🎯 Closing Line

Go ka concurrency model simple hai —
bas discipline aur idioms follow kar lo.
Channel aur goroutine sahi use kar liye toh likh lega tu bhi production-grade concurrent code 🚀