What Are Goroutines?

Key Characteristics

• Lightweight: Initial stack size of only ~2KB (vs 1-2MB for OS threads)
• Cheap to create: Can spawn millions of goroutines with minimal overhead
• Managed by Go runtime: Scheduler multiplexes goroutines onto OS threads
• Cooperative scheduling: Goroutines yield control at specific points
• Growing stacks: Stack grows and shrinks dynamically as needed
• No direct control: You cannot directly kill or pause a goroutine

Simple Example

go
package main

import (
    "fmt"
    "time"
)

func sayHello(name string) {
    fmt.Printf("Hello from %s!\n", name)
}

func main() {
    // Launch goroutines
    go sayHello("goroutine 1")
    go sayHello("goroutine 2")
    go sayHello("goroutine 3")
    
    // Wait for goroutines to finish
    time.Sleep(1 * time.Second)
    
    fmt.Println("Main function exits")
}

code
Hello from goroutine 3!
Hello from goroutine 1!
Hello from goroutine 2!
Main function exits