Posted in 2018

Python Matplotlib fails with “QXcbConnection: Could not connect to display”

Matplotlib is useful for interactive 2D plotting and also for batch production of plots inside a job. The default behavior is to do interactive plotting which requires the package to open a window on your display. For this purpose you have to log into mistral with X11 forwarding enabled.

 If you run matplotlib in a jobscript where you just want to create files of your plots, you have to tell matplotlib to use a non-interactive backend. See matplotlib’s documentation how to do that and which backends are available. Here is how to select the Agg backend (raster graphics png) inside your script. Add to the top of your imports

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How can I avoid core files if my program crashes

Core files can be very helpful when debugging a problem but they also take a long time to get written for large parallel programs. The following command will limit the core size to zero, i.e. no core files will be written:

The effect of the above command call can be checked with:

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