<div dir="ltr"><div>Dear Dr. Roland,</div><div><br></div><div>Thank you for your detailed response. I really appreciate the time and thought you must've put into it.</div><div><br></div><div>I have followed your suggestion of removing the current Cactus build and compiling it again but received yet another error. The problem seems to be a mixup of multiple MPI implementations, just as you had suggested. I couldn't finesse my way out of it, so I re-installed Ubuntu instead(deleting everything in the process) and began from scratch. I installed only those packages mentioned on the Jupyter tutorial and the code compiled successfully this time.</div><div><br></div><div>Thank you once again for your helpful advice.</div><div><br></div><div>Regards,</div><div>Praveer Krishna<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Mar 27, 2020 at 8:42 PM Roland Haas <<a href="mailto:rhaas@illinois.edu">rhaas@illinois.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hello Praveer Krishna,<br>
<br>
since mpirun was not found initially it would seem that you had not MPI<br>
stack installed when compiling Cactus.<br>
<br>
Cactus is best used with an MPI stack installed beforehand. The new<br>
user tutorial<br>
<br>
<a href="https://nbviewer.jupyter.org/github/nds-org/jupyter-et/blob/master/CactusTutorial.ipynb" rel="noreferrer" target="_blank">https://nbviewer.jupyter.org/github/nds-org/jupyter-et/blob/master/CactusTutorial.ipynb</a> <br>
<br>
contains instructions on how to install a set up packages that simplify<br>
building Cactus, including MPI. Did you follow those instructions or<br>
started from a vanilla, freshly installed OS? Also, what OS are you<br>
using (OSX, Linux, Linux-Subsystem-on-Windows)?<br>
<br>
The easiest way to get a working copy of Cactus, if you did not install<br>
an MPI stack before compiling Cactus, is:<br>
<br>
* install an MPI stack (OpenMPI is fine)<br>
* remove the current Cactus build using "rm -rf configs/sim"<br>
* build once more<br>
<br>
The solution above is the suggested solution.<br>
<br>
If you would like to avoid recompiling (and risk triggering other<br>
issues instead), here's an alternative: When it detected that no MPI<br>
stack was installed then Cactus built its own copy of OpenMPI. It will<br>
have copied "mpirun" to "exe/sim/mpirun" and you can use that by making<br>
sure that the full path to the directory "exe/sim" appears in your PATH<br>
before you start the simulation. Using an mpirun from a different MPI<br>
stack than the one used to compile Cactus is what gives the error that<br>
Erik descibes in the email you found.<br>
<br>
Yours,<br>
Roland<br>
<br>
> Dear ET Users,<br>
> <br>
> I'm a beginner attempting to follow the Jupyter tutorial for new users. I<br>
> have been able to successfully run the helloworld.par and tov_ET.par files<br>
> with procs set to 1 but I'm having issues when I try to use multiple<br>
> processors on my laptop.<br>
> I initially got this error <<a href="https://imgur.com/a/cuLLp79" rel="noreferrer" target="_blank">https://imgur.com/a/cuLLp79</a>> saying "mpirun:<br>
> not found", following which I installed Open MPI on my system. The error<br>
> persisted, so I removed Open MPI and installed mpich instead. This<br>
> seemingly fixed the issue, but I received another error<br>
> <<a href="https://imgur.com/gdXSqCj" rel="noreferrer" target="_blank">https://imgur.com/gdXSqCj</a>> saying "CACTUS_NUM_PROCS is set to 4 but there<br>
> are 1 MPI processes"<br>
> <br>
> I found one<br>
> <<a href="https://www.mail-archive.com/search?l=users@einsteintoolkit.org&q=subject:%22%5C%5BUsers%5C%5D+problem+on+running+bbh+expample%22&o=newest&f=1" rel="noreferrer" target="_blank">https://www.mail-archive.com/search?l=users@einsteintoolkit.org&q=subject:%22%5C%5BUsers%5C%5D+problem+on+running+bbh+expample%22&o=newest&f=1</a>><br>
> or two<br>
> <<a href="https://www.mail-archive.com/users@einsteintoolkit.org/msg01591.html" rel="noreferrer" target="_blank">https://www.mail-archive.com/users@einsteintoolkit.org/msg01591.html</a>><br>
> previous queries regarding this exact error, but the suggestions have not<br>
> worked for me so far. Having never worked with MPI before, I am not sure<br>
> what else I should try.<br>
> <br>
> I'd be grateful for a few words of advice on this issue from anyone in the<br>
> community.<br>
> Thank you in advance for your time.<br>
> <br>
> Regards,<br>
> Praveer Krishna<br>
<br>
<br>
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</blockquote></div>