context-cancel-in-loop

Default severity: warning

context.WithCancel, WithTimeout, and WithDeadline retain parent or timer resources until cancellation. A defer in the surrounding function runs too late; cancel during the iteration or move the body into a helper.

Bad

for _, item := range items {
  itemCtx, cancel := context.WithCancel(ctx)
  defer cancel()
  use(itemCtx, item)
}

Good

for _, item := range items {
  if err := handleItem(ctx, item); err != nil {
    return err
  }
}

func handleItem(ctx context.Context, item Item) error {
  itemCtx, cancel := context.WithCancel(ctx)
  defer cancel()
  return use(itemCtx, item)
}