inconsistent results

[Lydia Ickler <ic...@googlemail.com>]

Hi all,

I am doing a Power Iteration. When I execute it with one machine everything works great. 
When I use more than one (in my case 5) then I get different results.
I attached my code. 
Within the execution plan I can see that a GroupReduce part is executed only by one worker (see screenshot) - is this causing the issue?

Best regards, 
Lydia

Re: inconsistent results

[Aljoscha Krettek <al...@apache.org>]

Hi,
I don’t know about the results but one problem I can identify is this snipped:

groupBy(0).sum(2).max(2)

The max(2) here is a non-parallel operation since it finds the max over all elements, not grouped by key. If you want the max to also be per-key you have to use

groupBy(0).sum(2).andMax(2)

I hope that helps.

Cheers,
Aljoscha
> On 16 Feb 2016, at 12:30, Lydia Ickler <ic...@googlemail.com> wrote:
> 
> Hi all,
> 
> I am doing a Power Iteration. When I execute it with one machine everything works great. 
> When I use more than one (in my case 5) then I get different results.
> I attached my code. 
> Within the execution plan I can see that a GroupReduce part is executed only by one worker (see screenshot) - is this causing the issue?
> 
> Best regards, 
> Lydia
> 
> <PowerIteration.java>
> <Bildschirmfoto 2016-02-16 um 12.28.37.png>