Can you explain what an error group is and how it is used in monitoring or exception handling?

Error group — is a structure that allows you to combine multiple errors into one for convenient handling and returning. In Go, this is useful when you need to perform several operations in parallel and collect all errors that occur into a single object.

Example of using error group from the golang.org/x/sync/errgroup package:

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

func process() error {
    var g errgroup.Group

    g.Go(func() error {
        // first task
        return nil
    })

    g.Go(func() error {
        // second task
        return fmt.Errorf("error in second task")
    })

    // Wait for all tasks to complete and get the first error if any
    if err := g.Wait(); err != nil {
        return err
    }
    return nil
}

Thus, error group helps to conveniently aggregate errors from multiple goroutines and simplifies error handling.