MadGraph5_aMC@NLO

Segmentation fault in MG5aMC_PY8_interface

Asked by Bruno Miguel Silva de Oliveira

Hello,

I'm encountering a segmentation fault when attempting to simulate SM tqll events with MadGraph5_aMC@NLO and showering with Pythia8 through the MG5aMC_PY8_interface, at which the crash seems to be taking place.
The complete script and relevant log are included below.

Although this appears to be an issue related to Pythia8 or the MG5aMC_PY8_interface rather than MadGraph5_aMC@NLO itself, I would appreciate any guidance or suggestions on how to resolve or further diagnose the problem.

Thank you in advance for your attention.

Best regards,
Bruno

==================== Simulation ====================
# ----- Model -----
import model sm-no_masses

define p = g u u~ c c~ d d~ s s~ b b~
define j = g u u~ c c~ d d~ s s~ b b~
define qq = u u~ d d~ # also s, c, and b; but not needed for this example
define bb = b b~

define mu = mu+ mu-
define vmu = vm vm~

# ----- Simulation -----
generate p p > t qq mu mu, (t > mu vmu bb)
add process p p > t qq mu mu j, (t > mu vmu bb)

output FCChh/test.run

launch FCChh/test.run

shower=Pythia8
detector=OFF
analysis=OFF

done

# ----- Simulation Parameters -----
set pdlabel lhapdf

set maxjetflavor=5

set ickkw 1

set nevents 10000
set iseed 1

set ebeam1 50000
set ebeam2 50000

==================== MadGraph5_aMC@NLO Log ====================
NFO: Running Pythia8 [arXiv:1410.3012]
No user-defined value for Pythia8 parameter 'JetMatching:nJetMax'. Setting it automatically to 1.
Splitting .lhe event file for PY8 parallelization...
Submitting Pythia8 jobs...
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_20/run_PY8.sh: line 2: 25470 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
WARNING: program /mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_20/run_PY8.sh 20 launch ends with non zero status: 139. Stop all computation
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_27/run_PY8.sh: line 2: 25490 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_19/run_PY8.sh: line 2: 25468 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_17/run_PY8.sh: line 2: 25461 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_28/run_PY8.sh: line 2: 25494 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
Terminated
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_23/run_PY8.sh: line 2: 25479 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_2/run_PY8.sh: line 2: 25416 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_3/run_PY8.sh: line 2: 25418 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_14/run_PY8.sh: line 2: 25452 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_5/run_PY8.sh: line 2: 25425 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_7/run_PY8.sh: line 2: 25431 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
WARNING: program /mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_14/run_PY8.sh 14 launch ends with non zero status: 139. Stop all computation
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_8/run_PY8.sh: line 2: 25436 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
WARNING: program /mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_7/run_PY8.sh 7 launch ends with non zero status: 139. Stop all computation
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_12/run_PY8.sh: line 2: 25445 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
WARNING: program /mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_12/run_PY8.sh 12 launch ends with non zero status: 139. Stop all computation
Terminated
Exception in thread Thread-306 (worker):
Traceback (most recent call last):
  File "/usr/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.10/threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "/opt/MG5_aMC/madgraph/various/cluster.py", line 703, in worker
    self.demons.remove(threading.current_thread())
ValueError: list.remove(x): x not in list
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_13/run_PY8.sh: line 2: 25449 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
WARNING: program /mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_13/run_PY8.sh 13 launch ends with non zero status: 139. Stop all computation
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_9/run_PY8.sh: line 2: 25438 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
Exception in thread Thread-307 (worker):
Traceback (most recent call last):
  File "/usr/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.10/threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "/opt/MG5_aMC/madgraph/various/cluster.py", line 703, in worker
    self.demons.remove(threading.current_thread())
ValueError: list.remove(x): x not in list
Terminated
Terminated
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_44/run_PY8.sh: line 2: 25541 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
Terminated
WARNING: program /mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_44/run_PY8.sh 44 launch ends with non zero status: 139. Stop all computation
Exception in thread Thread-308 (worker):
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_15/run_PY8.sh: line 2: 25455 Segmentation fault (core dumped) ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
Traceback (most recent call last):
  File "/usr/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
Terminated
    self.run()
  File "/usr/lib/python3.10/threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "/opt/MG5_aMC/madgraph/various/cluster.py", line 703, in worker
Terminated
Terminated
    self.demons.remove(threading.current_thread())
ValueError: list.remove(x): x not in list
Terminated
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_55/run_PY8.sh: line 2: 25574 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_42/run_PY8.sh: line 2: 25536 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
Terminated
WARNING: program /mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_55/run_PY8.sh 55 launch ends with non zero status: 139. Stop all computation
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_30/run_PY8.sh: line 2: 25501 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
Terminated
Terminated
/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_52/run_PY8.sh: line 2: 25567 Segmentation fault ./MG5aMC_PY8_interface PY8Card.dat &> PY8_log.txt
Terminated
Terminated
Terminated
Terminated
Terminated
Pythia8 shower jobs: 1 Idle, 33 Running, 66 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 32 Running, 68 Done [14 seconds]
Terminated
Pythia8 shower jobs: 0 Idle, 31 Running, 69 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 30 Running, 70 Done [14 seconds]
Terminated
Pythia8 shower jobs: 0 Idle, 29 Running, 71 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 28 Running, 72 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 27 Running, 73 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 26 Running, 74 Done [14 seconds]
Terminated
Pythia8 shower jobs: 0 Idle, 25 Running, 75 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 23 Running, 77 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 22 Running, 78 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 21 Running, 79 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 20 Running, 80 Done [14 seconds]
Terminated
Pythia8 shower jobs: 0 Idle, 18 Running, 82 Done [14 seconds]
Terminated
Terminated
Pythia8 shower jobs: 0 Idle, 16 Running, 84 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 15 Running, 85 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 14 Running, 86 Done [14 seconds]
Terminated
Pythia8 shower jobs: 0 Idle, 13 Running, 87 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 11 Running, 89 Done [14 seconds]
Terminated
Terminated
Pythia8 shower jobs: 0 Idle, 8 Running, 92 Done [14 seconds]
Terminated
Pythia8 shower jobs: 0 Idle, 5 Running, 95 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 3 Running, 97 Done [14 seconds]
Pythia8 shower jobs: 0 Idle, 2 Running, 98 Done [14 seconds]
Terminated
Pythia8 shower jobs: 0 Idle, 0 Running, 100 Done [14 seconds]
Merging results from the split PY8 runs...
Command "generate_events run_01" interrupted with error:
InvalidCmd : Could not find cross-section and event number information in Pythia8 log
          '/mnt/nvme1n1p1/Heavy-Neutrino-Antineutrino-Oscillations/FCChh/test.run/Events/run_01/PY8_parallelization/split_0/PY8_log.txt'.

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

As you said, this sounds a pythia error, and I would say that you should ask pythia author for help.
Now the issue is that the error might be in the interface script which was written by an old pythia8 author and distributed outside of both madgraph and pythia8. Meaning that Pythia8 author do not really support it (neither do I) and therefore some pythia8 authors sometimes said that this is a MG5 issue... Therefore maybe the best is to create an issue on the Pythia8 gitlab and ping me on the issue such that I can help as much as I can. (but at least we will all be around the same discussion thread).

My only suggestion would be to change the model to use a model where the b quark is massless since you seem to want to use a 5flavor computation but your model is actually 4 flavor. Maybe this is what triggers the Pythia8 issue since some of your parameter are set in 5 flavor but not all (a_s running is still in 4 flavor for example).
But to be honest, I have kind of no clue on why pythia8 is crashing and therefore this is more a physics suggestion.

Cheers,

Olivier

Revision history for this message
Bruno Miguel Silva de Oliveira (bruno-miguel-oliveira) said : 		#2

Hi,

Thank you for your suggestion. I was actually using sm-no_masses, which I believe should be compatible with a five-flavour computation — I mistakenly wrote sm-lepton_masses in my original question.

Following your advice, I’ve opened an issue at https://gitlab.com/Pythia8/releases/-/issues/588 and pinged you there.

I’ll keep this question open for now so I can update it with the solution later, for future reference.

Best regards,
Bruno

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