Concurrency

Concurrency is one of Go's greatest strengths. Go was designed from the ground up to make concurrent programming simple and efficient. The key primitives are goroutines (lightweight threads) and channels (typed communication pipes).

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Goroutines

A goroutine is a lightweight thread managed by the Go runtime:

func sayHello() {
    fmt.Println("Hello from goroutine!")
}

func main() {
    go sayHello()           // launch a goroutine
    time.Sleep(time.Second) // wait for it to finish (crude approach)
}

Goroutine Properties

Property	Description
Cost	~2 KB initial stack (grows as needed) — much cheaper than OS threads
Scheduling	Managed by the Go runtime, not the OS
Scalability	Easily run millions of goroutines
Launch syntax	go functionCall()
Return values	Cannot return values directly — use channels

Anonymous Goroutines

go func() {
    fmt.Println("Anonymous goroutine")
}()

go func(msg string) {
    fmt.Println(msg)
}("Hello")

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Channels

Channels are typed conduits for communication between goroutines:

ch := make(chan string)   // unbuffered channel of strings

go func() {
    ch <- "hello"         // send to channel
}()