[Paraview] xdmf writer in parallel

[Biddiscombe, John A.]

Dave et al,

The XdmfWriter in paraview won't write in parallel. The main reason being that the hyperslab assignment just isn't implemented for a dataset which is split into pieces, and for a multiblock dataset there is no provision to write one block per dataset into the file.

We implemented our own version which does write in parallel, but the code is/has been unused for some time (almost certainly broken now) and relies on fudges we made to Xdmf which although they worked very well, haven't been maintained because I had hoped to port the lot to the new Xdmf which is a much cleaner code and supports 'visitor' style patterns natively which makes it easier to hook custom actions to a tree of datasets traversal (such as writing out to file)

Our writer used this small utility library to help out
https://hpcforge.org/plugins/mediawiki/wiki/libh5mb/index.php/Main_Page

If it was a matter of life and death, I could probably get the code working (the vtkXdmfWriter2 or whatever we called it), but it'd take a couple of days and isn't something I was desperately in need of right now.

Off topic: I started work on porting all our xdmf developments to the 'new' xdmf library but when I saw how much work was needed for the vtkXdmfReader I gave up (I did get the XdmfGenerator project running with the new library https://hpcforge.org/plugins/mediawiki/wiki/xdmfgenerator/index.php/Main_Page , but not production ready and certain features like JOIN $1,$2,$3 were not yet supported in Xdmf2, which we really needed for our stuff). I'd like to revisit this whole topic and would welcome encouragement. Since the Xdmf chaps have not been very active on the lists, it has been hard to work up much enthusiasm to develop/extend the codes....

JB

-----Original Message-----
From: paraview-bounces at paraview.org [mailto:paraview-bounces at paraview.org] On Behalf Of David E DeMarle
Sent: 13 April 2012 16:13
To: Utkarsh Ayachit
Cc: paraview at paraview.org
Subject: Re: [Paraview] xdmf writer in parallel

I vaguely recall that it won't work in parallel because we don't use the parallel flavor of hdf5, and because we didn't want to automatically gather before writing in serial.

John Biddiscombe, does this sound right to you?

David E DeMarle
Kitware, Inc.
R&D Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909



On Fri, Apr 13, 2012 at 9:05 AM, Utkarsh Ayachit <utkarsh.ayachit at kitware.com> wrote:
> Looking at the xmls definition, no, it doesn't look like it supports 
> parallel. Dave, is that for real or an oversight?
>
> Utkarsh
>
> On Thu, Apr 12, 2012 at 3:44 PM, Burlen Loring <bloring at lbl.gov> wrote:
>>
>> XDMF writer disappears as an option from the save dialog when I run 
>> with mpi and np is more than 1. However, when run in serial or with 
>> np 1 it is available. Can the XDMF writer write in parallel?
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