Concurrency in Go/

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WaitGroup

WaitGroup

Learn about WaitGroup in the sync package.

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Overview of WaitGroup

In lots of previous code, we have encountered the following code lines:

wg.Add()

Or

wg.Wait()

Or

wg.Done()

What exactly do these lines mean? The wg is a variable-holding instance for sync.WaitGroup. Use WaitGroup to wait for all the launched goroutines.

var wg sync.WaitGroup

Requirement of WaitGroup

In order to understand the need for WaitGroup, let’s walk through some simple code.

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package main
import (
	"fmt"
)
func main() {
	go func() {
		fmt.Println("I am goroutine 1")
	}()
	go func() {
		fmt.Println("I am goroutine 2")
	}()
}

The code above won’t print anything, but why is that? Let’s see what’s happening behind the scenes to understand this.

The moment the Go compiler starts executing the main.go file, it encounters the main goroutine (primary function). The compiler then launches the other two anonymous goroutines as well. Since ...