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In ParaView, the prefix "Para" stands for "parallel" : How can we activate parallelism in ParaView ?
How to use this tutorial
- This tutorial was only tested with the release 5.5.2 of ParaView
- If you have data to be visualized by ParaView, you can use your data.
- If you don’t have data yet, you can use some little scripts [37] written in python :
- first, copy the scripts to your personal disk space
- Start paraview (see under)
- you can read one script with the menu item :
View/Python shell/Run script
module load paraview/5.5.2 cp -r $PARAVIEW_ROOT/examples/python-scripts .
Starting a graphics session
ParaView must be used from a graphics session. Because we want to visualize very big datasets, we probably need more memory than the default. We must also specify that we want more than 1 core.
The complete story is here. You can use the following command to start a graphics session:
runVisuSession.sh --cpus-per-task 4 --mem 40G
Starting a visualization server
The ParaView gui cannot use several cores. Only the readers and the visualization engines can use several cores. So we must start a server process, using mpi to make it to work in parallel. As we have 4 cores in this session, let’s dedicate 3 of them to the server, keeping 1 core for the gui.
Open a terminal and type the following :
$ mpirun -np 3 pvserver --disable-xdisplay-test Waiting for client... Connection URL: cs://olympevolta11.bullx:11111 Accepting connection(s): olympevolta.bullx11:11111
Starting the ParaView gui
Start ParaView version 5.5.2, using the main graphics menu : put the mouse over the root window, click with the right button, and choose the item:
Visualization_Applications/Paraview
Configuring the connection
The procedure described here should be done only the first time : the configured connection(s) will be kept from session to session.
- When Paraview is started, click on the menu item :
File/connect
- A window entitled
Choose Server Configuration
opens, click the buttonAdd Server
- A window entitled
Edit Server Configuration
opens with several fields, all fields being already filled. Modify the value of the field Name, writing the name you choose for the connection : saymy_pvserver
, then click the buttonConfigure
- A window entitled
Edit Server Launch Configuration
opens, just click the buttonSave
Connecting to the pvserver
If not already done, start Paraview and click the menu item : File/connect
, then select the my_pvserver
line and click the Connect button. You are now connected to the pvserver, as indicated in the Pipeline browser window (see figure)
![connection window](/public/inline-images/my_pvserver.png)
Besides, if you look at the window from which you launched pwserver, you should see this message :
Client connected
Loading and displaying data
- Figure obtained with 4 processors, using the python script rectilinear.py
You can now load your datafiles, your state files, your python scripts, exactly as usual.
Warning : to read a python script, you must use the menu item : View/Python shell/Run script
.
Data will be read by pvserver, and rended and displayed by ParaView. You should have a new property available with your data : vtkProcessId
You can easily display the domain decomposition made pvserver for reading your data (see the figure).
If you execute a filter, it will be executed by pvserver, thus using several cores, which can lead to faster execution if you have a huge quantity of data to treat
(1) We thank M. Jean Favre, from CSCS, who authorized us to share those scripts