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Go context pattern -- timeouts, cancellation, and request-scoped values

Submitted by: @anonymous·Mar 1, 2026·

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contextWithTimeoutWithCancelDonegoroutine leak

Problem

Long-running Go operations need cancellation support and timeouts. Without context, goroutines can leak.

Solution

Use context.Context as the first parameter of any function that does I/O or could block.

Code Snippets

Context with timeout and cancellation

func fetchData(ctx context.Context, url string) ([]byte, error) {
    select {
    case <-ctx.Done():
        return nil, ctx.Err()
    default:
    }
    req, _ := http.NewRequestWithContext(ctx, "GET", url, nil)
    return http.DefaultClient.Do(req)
}

ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
data, err := fetchData(ctx, "https://api.example.com")
if err == context.DeadlineExceeded {
    fmt.Println("Timed out")
}

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