Is a valid hashCode on Coder part of our contract or not? If it is, then
the lack of hashCode on SchemaCoder is simply a bug.
On Thu, May 9, 2019 at 7:42 AM Jan Lukavský <je...@seznam.cz> wrote:
> Hi,
>
> I have spent several hour digging into strange issue with DirectRunner,
> that manifested as non-deterministic run of pipeline. The pipeline
> contains basically only single stateful ParDo, which adds elements into
> state and after some timeout flushes these elements into output. The
> issues was, that sometimes (very often) when the timer fired, the state
> appeared to be empty, although I actually added something into the
> state. I will skip details, but the problem boils down to the fact, that
> StateSpecs hash Coder into hashCode - e.g.
>
> @Override
> public int hashCode() {
> return Objects.hash(getClass(), coder);
> }
>
> in ValueStateSpec. Now, when Coder doesn't have hashCode and equals
> implemented (and there are some of those in the codebase itself - e.g.
> SchemaCoder), it all blows up in a very hard-to-debug manner. So the
> proposal is - either to add abstract hashCode and equals to Coder, or
> don't hash the Coder into hashCode of StateSpecs (we can generate unique
> ID for each StateSpec instance for example).
>
> Any thoughts about which path to follow? Or maybe both? :)
>
> Jan
>
>
>
