Comment 0 for bug 1716425

Hi,

When showering with Pythia8 with just one core, showering fails. The error one gets is

Pythia8 cross-section could not be retreived.
Try turning parallelization off by setting the option nb_core to 1.

The given message doesn't make sense, since I am actually running on single core mode. Strangely, the problem only arises when working with only one core, with generate_events --nb_core=1. Using generate_events --nb_core=2 fixes the issue (unfortunately, when running on clusters, system administrators usually ask you to avoid multi-threaded code, so in those cases using nb_core=2 would not help).

Further information:
Options are set in mg5 with
set run_mode 2
set nb_core 1
save options

Events are being run with madevent:
generate_events runname --nb_core=1
shower=PYTHIA8

Technical details:
Running madgraph 2.6.0
Pythia8
Python 2.7.13
gcc (GCC) 6.2.0

I attach the MG5 output file

Thanks!

Daniel