How to Use errgroup for Structured Concurrency

Use errgroup to run multiple goroutines concurrently while automatically canceling remaining tasks if any one fails. Create a group with WithContext, launch tasks using g.Go, and wait for completion with g.Wait to retrieve the first error.

package main

import (
	"context"
	"fmt"
	"time"

	"golang.org/x/sync/errgroup"
)

func main() {
	ctx := context.Background()
	g, ctx := errgroup.WithContext(ctx)

	for i := 0; i < 3; i++ {
		i := i
		g.Go(func() error {
			time.Sleep(time.Second)
			if i == 1 {
				return fmt.Errorf("task %d failed", i)
			}
			fmt.Printf("task %d done\n", i)
			return nil
		})
	}

	if err := g.Wait(); err != nil {
		fmt.Println("Error:", err)
	}
}

Think of errgroup as a team manager for your background tasks. It starts multiple workers at once and ensures that if one worker fails, the manager immediately stops everyone else to save resources. You use it when you need to run several independent jobs in parallel but want to stop everything the moment a single job goes wrong.