export_meta() not working with multiprocessing

[nicoeinsidler]

Multiprocessing not working

Note: This issue was migrated over from Bitbucket.

I ran into this problem when I introduced export_meta() in the Measurement class. When performance becomes an issue, this should be fixed again, but for now the sequential analysis works quite fast.

Terminal output on this one:

✅  testfiles\2019_02_20_1340_dc2z_scan.dat: Detected measurement type DC.
📍  testfiles\subdirectory_test\2018-11-23-0900-degree-of-polarisation.pos: Position file read: testfiles\2018-11-23-1325-degree-of-pol.dat
multiprocessing.pool.RemoteTraceback:
"""
Traceback (most recent call last):
  File "C:\Users\Nico Einsidler\AppData\Local\Programs\Python\Python37-32\lib\multiprocessing\pool.py", line 121, in worker
    result = (True, func(*args, **kwds))
  File "C:\Users\Nico Einsidler\AppData\Local\Programs\Python\Python37-32\lib\multiprocessing\pool.py", line 44, in mapstar
    return list(map(*args))
  File "C:\Users\Nico Einsidler\Documents\pigor\measurement.py", line 707, in export_meta
    if self.popt:
AttributeError: 'Measurement' object has no attribute 'popt'
"""

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "pigor.py", line 121, in <module>
    main()
  File "pigor.py", line 117, in main
    analyse_files(all_files)
  File "pigor.py", line 72, in analyse_files
    pool.map(measurement.Measurement.export_meta, m)
  File "C:\Users\Nico Einsidler\AppData\Local\Programs\Python\Python37-32\lib\multiprocessing\pool.py", line 268, in map
    return self._map_async(func, iterable, mapstar, chunksize).get()
  File "C:\Users\Nico Einsidler\AppData\Local\Programs\Python\Python37-32\lib\multiprocessing\pool.py", line 657, in get
    raise self._value
AttributeError: 'Measurement' object has no attribute 'popt'