SegFault

[aFuerst]

I'm opening a geotif file in a function call and setting it's raster band to an instance variable in a class. Later when trying to access data from the raster in another function, it throws a segfault and kills the program

[aFuerst]

Contains the code I'm working with and experiencing the error

[Even Rouault]

You're running into one of the gotchas explained in ​https://trac.osgeo.org/gdal/wiki/PythonGotchas

The issue is in

  def _openFile(self):
        f = gdal.Open(self.file_name)
        self.open_file = f.GetRasterBand(1)

Basically as soon as this function returns the dataset is closed because no Python object retains a reference to it, so the self.open_file points to a defunct C++ object. Workaround: maintain the reference to f alive while you work on the band object