On Thu, Jul 21, 2022 at 11:02 AM Michal Hruby <michal....@gmail.com> wrote:
>
> Hello, I have a code snippet equivalent to this one:
>
> rows, err := stmt.QueryContext(ctx)
> if err != nil {
> return info, nil, err
> }
> defer rows.Close()
>
> var data sql.RawBytes
> for rows.Next() {
> err = rows.Scan(&data)
> if err != nil {
> return nil, err
> }
> // if ctx is canceled around this point, rows.Close() will be called and
> the data can e overwritten, causing a data race
> _ = data[0] // <--- possible concurrent read here and write inside
> driver.Rows.Close()
> }
>
> And as the comments say, if the context is cancelled, there's a possibility
> of a data race where this goroutine is trying to read data[0], and another
> goroutine can be writing to it, cause the sql package calls
> driver.Rows.Close() (from
> https://github.com/golang/go/blob/176b63e7113b82c140a4ecb2620024526c2c42e3/src/database/sql/sql.go#L2974
> )
>
> I've opened an issue about this on github (
> https://github.com/golang/go/issues/53970 ), but was told that's not the
> proper forum to talk about data races.
>
> Any help would be appreciated, thanks.
I don't quite understand what you are asking. I think you're correct
that there is a data race there. It seems to me that the answer is to
not cancel the context.
What kind of answer are you looking for?
Ian
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