# mpiexec utility
**URL:** https://discourse.paraview.org/t/mpiexec-utility/7570
**Category:** ParaView Support
**Created:** [July 8, 2021, 11:55am UTC](https://discourse.paraview.org/t/mpiexec-utility/7570 "2021-07-08T11:55:00Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Captain\_Convergence](https://discourse.paraview.org/u/Captain_Convergence)
#### Post date: [July 8, 2021, 11:55am UTC](https://discourse.paraview.org/t/mpiexec-utility/7570/1 "2021-07-08T11:55:00Z")
Hi everyone!
I am having problems when using parallel post-processing with the mpiexec utility. The issue is that I cannot make paraview plot graphs when using multiple CPUs. At the beginning it wasn’t a big problem because the simulations were quite light but now I am switching to heavier simulations and this is delaying significantly my post-processing. Here I leave an example of how I call paraview with mpiexec with a single and multiple CPUS
**Single CPU**
**time mpiexec -np 1 pvbatch --force-offscreen-rendering myscript.py**
**Multiple CPUs**
**time mpiexec -np 6 pvbatch --force-offscreen-rendering myscript.py**
I have noticed that when using multiple CPUs the graphs are not plotted (in this case the _Plot Data Over Time_ filter) and that the axis title labels (X(m) and Z(m)) are thicker like if there were several characters overlapped.
I would like to know if there is an specific command for the mpiexec utility to control which CPU takes care of each process because it seems that the CPU are failing to communicate properly.
Thank you in advance!
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [July 8, 2021, 11:57am UTC](https://discourse.paraview.org/t/mpiexec-utility/7570/2 "2021-07-08T11:57:02Z")
please share your script
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### Author:  [@Captain\_Convergence](https://discourse.paraview.org/u/Captain_Convergence)
#### Post date: [July 8, 2021, 12:04pm UTC](https://discourse.paraview.org/t/mpiexec-utility/7570/3 "2021-07-08T12:04:26Z")
Hi Mathieu,
Thank you so much for you quickly response. I think that the problem is not in the script since it works perfectly fine when using 1 CPU. Anyways you have here my script :
[post\_process\_video\_streaklines\_CL.py](https://discourse.paraview.org/uploads/short-url/6b4TTdkmIy0WU5VTgpYKOIQQyok.py) (40.8 KB)
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### Author:  [@Captain\_Convergence](https://discourse.paraview.org/u/Captain_Convergence)
#### Post date: [July 8, 2021, 1:31pm UTC](https://discourse.paraview.org/t/mpiexec-utility/7570/4 "2021-07-08T13:31:14Z")
Hi again,
I found the problem, it is linked with the name of the variables. Below you have an example of the same script opened in serial (left) and the script opened in parallel using pvserver (right). I found that when plotting data over time, the variable name is modified.
Since I was addressing to “cl (stats)”, nothing was plotted in parallel because the variable is named now “cl (stats rank=0)”.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [July 8, 2021, 1:33pm UTC](https://discourse.paraview.org/t/mpiexec-utility/7570/5 "2021-07-08T13:33:54Z")
Which filter generate this output ?
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### Author:  [@Captain\_Convergence](https://discourse.paraview.org/u/Captain_Convergence)
#### Post date: [July 8, 2021, 1:35pm UTC](https://discourse.paraview.org/t/mpiexec-utility/7570/6 "2021-07-08T13:35:21Z")
The _Plot Data Over Time_ filter. My data is named x,z,cd,cl etc… but this filter adds the (stats…) extension.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [July 8, 2021, 1:38pm UTC](https://discourse.paraview.org/t/mpiexec-utility/7570/7 "2021-07-08T13:38:27Z")
This filter was reworked very recently by @Yohann_Bearzi , so maybe this is fixed in master already.