[Paraview] pvbatch, MPI and MultiBlock data sets

[Yves Rogez]

Hi,

I found a solution to this problem. I had to insert an UpdatePipeline() 
call just before the writer update :

    /myLastFilter.UpdatePipeline()
    writer.UpdatePipeline()/

This is a strange behavior. Maybe due to MPICH2 usage ? I don't know... 
However it runs well like that.

Thanks for your help

Yves


    Le mardi 29 janvier 2013 15:56:32, Utkarsh Ayachit a écrit :

>
> Yves,
>
> 1. I don't see the oddity with the block number and BlockID when
> running in parallel, as you describe. For me, the BlockID in indeed
> Index for block + 1 whether I run in parlalel or not.
> 2. Running your python script as a single process, I get 1:18 minutes,
> while in parallel (2 procs), I get 1:22 mins. Given that your dataset
> very small and the computation done also very trivial (you are
> transforming 50 points!), it's not surprising that the overheads of
> parallel processing (interprocessing communication for various steps
> in the pipeline execution) make things slower. Try doing the same with
> a multiblock having thousands of points in each block and then you'll
> see the different
>
> Utkarsh
>
>
>
> On Tue, Jan 15, 2013 at 11:17 AM, Yves Rogez
> <yves.rogez at obs.ujf-grenoble.fr> wrote:
>>
>> Ok, trying ProcessIdScalars filter obliged me to see the results more in
>> details (with spreadsheet view).
>>
>> My input : 50 blocks containing each 1 polydata constituted by 1 
>> point and 1
>> vertex cell
>>
>> With a single process :
>> I get 50 blocks containing 1 point and 1 vertex cell, with PID = 0,
>> block number = ( index of the block + 1 )
>> So it is OK
>>
>> With MPI (2 processes) :
>> I get 50 blocks containing 2 points and 2 vertices cells, each with
>> strange block numbers :
>> block id 0 -> pt 1 has BN=2, pt 2 has BN=3
>> block id 1 -> BN=(5,6)
>> block id 2 -> BN=(8,9)
>> block id 3 -> BN=(11,12) and so on...
>> It seems :
>> BN for Point1 = ( ( BlockID + 1 ) * 3 ) - 1
>> BN for Point2 = ( BlockID + 1 ) * 3
>>
>> Point 1 of a block has always PID=0 and point 2 PID=1
>>
>> Maybe I made something wrong when generating my input (please find 
>> attached
>> a zip) ?
>>
>> Yves Rogez
>>
>> IPAG
>> Institut de Planétologie et d'Astrophysique de Grenoble
>> Bat D de Physique - BP. 53 - 38041 Grenoble - FRANCE
>>
>> tel : +33 (0)4 76 63 52 80
>> lab : +33 (0)4 76 63 52 89
>> Le 15/01/2013 16:25, Utkarsh Ayachit a écrit :
>>
>> Just to make sure, your ParaView is built with MPI support enabled,
>> right? XMLMultiBlockDataReader does distribute the blocks to read
>> among the processes. Try apply a "ProcessIdScalars" filter in the
>> middle and then look at the ProcessId assigned to the blocks in the
>> data. They should show how the blocks were distributed.
>>
>> Utkarsh
>>
>> On Tue, Jan 15, 2013 at 7:20 AM, Yves Rogez
>> <yves.rogez at obs.ujf-grenoble.fr> wrote:
>>
>> Hello,
>>
>> I'm trying to parallelize a process using pvbatch and MPI, with 
>> MultiBlock
>> data set; thus using the vtk composite pipeline.
>> I made a sample python program that is representative of what I have 
>> to do :
>>
>> --------------------------------------------------------------------------------------------------
>>
>> from paraview.simple import *
>>
>> r = servermanager.sources.XMLMultiBlockDataReader()
>> r.FileName = "input.vtm"
>>
>> # Defining a sample fake data processing
>> nbTs = 1000
>> ts = {}
>> for tIndex in range( 0, nbTs ):
>> ts[tIndex] = servermanager.filters.Transform()
>> if tIndex == 0:
>> ts[tIndex].Input = r
>> else:
>> ts[tIndex].Input = ts[tIndex - 1]
>> ts[tIndex].Transform.Scale = [1.01,1.01,1.01]
>>
>> w = servermanager.writers.XMLMultiBlockDataWriter()
>> w.Input = ts[nbTs - 1]
>> w.FileName = "output.vtm"
>>
>> w.UpdatePipeline()
>>
>> --------------------------------------------------------------------------------------------------
>>
>> I launch that using "mpiexec -np 4 pvbatch myscript.py"
>> All run well but I get a longer time using MPI than using only "pvbatch
>> myscript.py".
>>
>> By monitoring RAM, I noticed that it seems the data is loaded on time 
>> by MPI
>> process, and (maybe) all the MPI processes do exactly the same job,
>> computing four times all the data.
>>
>> Why my blocks in MultiBlock data set aren't dispatched over the MPI
>> processes ?
>> What am I doing wrong ?
>>
>> Many thanks for any help,
>>
>> Yves
>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the ParaView Wiki at:
>> http://paraview.org/Wiki/ParaView
>>
>> Follow this link to subscribe/unsubscribe:
>> http://www.paraview.org/mailman/listinfo/paraview
>>
>>
>> -- 
>> Yves Rogez
>> IPAG / CNRS
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.paraview.org/pipermail/paraview/attachments/20130204/969925ce/attachment-0001.htm>