How to Use errgroup for Concurrent Tasks in Go

Use errgroup.WithContext to create a group and context, then call g.Go for each task and g.Wait to block until completion or the first error.

package main

import (
	"context"
	"fmt"
	"golang.org/x/sync/errgroup"
	"time"
)

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

	for i := 0; i < 3; i++ {
		i := i // capture loop variable
		g.Go(func() error {
			select {
			case <-time.After(100 * time.Millisecond):
				return fmt.Errorf("task %d failed", i)
			case <-ctx.Done():
				return ctx.Err()
			}
		})
	}

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

Errgroup lets you run multiple Go routines at the same time and wait for them all to finish. If any one of them fails, it automatically stops the others and returns the error. Think of it like a team of workers where if one person trips, the whole crew stops immediately to handle the problem.