MadGraph5_aMC@NLO

MadGraph freezes when creating matching plots

Asked by Jean-Loup Tastet

When using MadGraph 3.5.x on macOS Sonoma (14.3.1) with parton shower performed by Pythia8 using the built-in interface, MadGraph always freezes (with no significant CPU usage) and never terminates while creating the matching plots:

...
Pythia8 shower jobs: 0 Idle, 0 Running, 10 Done [24 seconds]
Merging results from the split PY8 runs...
INFO: Create matching plots for Pythia8
^Crm jobs on queue
INFO: Stop by the user

This happens for a variety of processes, models and parameters. A minimal example that produces the issue on my machine is:

>generate p p > j j
>add process p p > j j j
>launch
>shower=Pythia8
>done
>done

Looking at the output, the .lhe and .hepmc event files are successfully generated, as well as the .gnuplot files, the .HwU files, and a single .ps file (that contains a correct-looking plot after I manually convert it to PDF using ps2pdf).

> > ls -1 PROC_sm_0/HTML/run_01/tag_1_PY8_plots/
central_qCut_djr_plots.HwU
central_qCut_djr_plots.gnuplot
central_qCut_pt_plots.HwU
central_qCut_pt_plots.gnuplot
min_max_qCut_djr_comparison.HwU
min_max_qCut_djr_comparison.gnuplot
min_max_qCut_pt_comparison.HwU
min_max_qCut_pt_comparison.gnuplot
qCut_67.5_djr_plots.HwU
qCut_67.5_djr_plots.gnuplot
qCut_67.5_djr_plots.ps
qCut_67.5_pt_plots.HwU
qCut_67.5_pt_plots.gnuplot
qCut_90_djr_plots.HwU
qCut_90_djr_plots.gnuplot
qCut_90_pt_plots.HwU
qCut_90_pt_plots.gnuplot

I remember this same install working about a year ago, but both MadGraph and the OS have been updated in the meantime. I tried again with a clean install of MadGraph 3.5.3, with the exact same result.

Looking at how a single .ps file is present, and considering the removal of PostScript in macOS Sonoma, makes me suspect that this could be related to the issue.

I am running MadGraph within a virtual environment with Python 3.10.9 and the following packages installed:

> pip freeze
attrs==22.2.0
click==8.1.3
cycler==0.11.0
jsonpatch==1.32
jsonpointer==2.3
jsonschema==4.17.3
kiwisolver==1.4.4
lxml==4.9.2
matplotlib==3.2.2
numpy==1.24.2
pyhf==0.6.3
pyparsing==3.0.9
pyrsistent==0.19.3
python-dateutil==2.8.2
PyYAML==6.0
scipy==1.10.1
six==1.16.0
tqdm==4.64.1

gnuplot, ps and ps2pdf are all in the PATH.

Do you know how to fix or work around this issue? Feel free to request any additional information or tests.

Thanks!

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MadGraph5_aMC@NLO Edit question
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Solved by:
Olivier Mattelaer
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Olivier Mattelaer (olivier-mattelaer) said : 		#1

My guess is that gnuplot is responsible for this?
Could you remove it from the path to see if this fix your issue?

Cheers,

Olivier

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Jean-Loup Tastet (jltastet) said : 		#2

Thanks for the incredibly fast answer!

I uninstalled gnuplot, and it indeed allowed MadGraph to finish. However, I now only have the matching plots in .HwU and .gnuplot formats (they are also missing from the MadAnalysis output, but this might be user error; I’ll double-check my cards).

Cheers,
Jean-Loup

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Best Olivier Mattelaer (olivier-mattelaer) said : 		#3

Then maybe you can run gnuplot by hand on one of those files to see if gnuplot provides information on the why he is freezing...

Cheers,

Olivier

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Jean-Loup Tastet (jltastet) said (last edit ): 		#4

Running gnuplot manually (as `gnuplot qCut_67.5_djr_plots.gnuplot`) successfully generates the plot, but with a number of warnings:

-p destination: Broken pipe # Repeated a dozen times or so

plot2d.c:702 caught a complex value # Repeated hundreds of times

"qCut_67.5_djr_plots.gnuplot" line 149: warning: Did you try to plot a complex-valued function?
"qCut_67.5_djr_plots.gnuplot" line 153: warning: could not confirm linked axis inverse mapping function
             y axis min/max 0.00010778 0.50554 data_min/max 0.00015141 0.0437186
                set_min/max -2.8242 11.603 link: primary y
    primary y axis min/max -3.96746 -0.296244 data_min/max 0.00015141 0.0437186
                set_min/max nan 1.06457 link: none

Line 149 is: unset label
Line 153 is: set size 1.0000e+00, 1.5000e-01

Reinstalling/upgrading gnuplot also didn’t solve the freezing problem when running MadGraph.

> gnuplot --version
gnuplot 6.0 patchlevel 0

> which gnuplot
/opt/homebrew/bin/gnuplot

If you want, I can send you the .gnuplot file and the full output by email. And as a temporary workaround, I can try to install it out-of-path (EDIT: since I only use gnuplot for MadGraph, the easiest fix was just to rename the gnuplot executable).

Cheers,
Jean-Loup

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Jean-Loup Tastet (jltastet) said : 		#5

Thanks Olivier Mattelaer, that solved my question.