中文
devexamples

Parallel Fetch With errgroup

Fetch several resources concurrently with errgroup so the first error cancels the rest and the combined call fails fast.

GoData Fetching

Code

snippet
package golang

import (
	"context"
	"fmt"

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

func fetch(ctx context.Context, url string) (string, error) {
	if url == "" {
		return "", fmt.Errorf("empty url")
	}
	return "body(" + url + ")", nil
}

func FetchAll(ctx context.Context, urls []string) ([]string, error) {
	group, ctx := errgroup.WithContext(ctx)
	results := make([]string, len(urls))
	for i, url := range urls {
		i, url := i, url
		group.Go(func() error {
			body, err := fetch(ctx, url)
			if err != nil {
				return err
			}
			results[i] = body
			return nil
		})
	}
	if err := group.Wait(); err != nil {
		return nil, err
	}
	return results, nil
}

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