The go keyword

Learn to run a function in the background with the go keyword.

The go keyword

The go keyword launches a function call as a goroutine. The call returns immediately; the function keeps running in the background. The caller moves to the next line without waiting.

Example: go doWork() starts doWork in the background. If the function returns a value you cannot get it directly; you need a channel or shared state.

Multiple go statements launch parallel work. But if the main program exits all goroutines die; so synchronization matters.

go and anonymous functions

It is common to use go with an anonymous function (closure): go func() { ... }(). This is the shortest way to run a small piece of code in the background.

An anonymous function can capture outer variables (closure). But be careful with loop variables: each iteration shares the same one. Passing as a parameter is safe.

Go 1.22 makes loop variables per-iteration; this fixes the classic pitfall.

Exercise Write an anonymous goroutine

Inside main, add a go func(){...}() expression and print anonymous ran with fmt.Println.

Show example solution

package main

import "fmt"

func main() {
    go func() {
        fmt.Println("anonim çalıştı")
    }()
    fmt.Println("anonim çalıştı")
}

Test yourself

What does the call go doWork() return?
- doWork's return value
- A channel
- Returns immediately, no value
- An error
Show answer

Returns immediately, no value — returns immediately. A goroutine's return value cannot be fetched directly.

Anonymous goroutine

Anonymous function in the background:
____ func() {
    fmt.Println("ok")
}()

Show answer

Anonymous function in the background:
go func() {
    fmt.Println("ok")
}()

Match go usages

go f()

Function goroutine
go func(){}()

Anonymous goroutine
go

Keyword
main

Main goroutine

Next lesson: Goroutine and function

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