Fixed multiprocessing issue (daemonic processes are not allowed to have children).

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>

gms_preprocessing/algorithms/L2B_P.py

@@ -77,7 +77,10 @@ class L2B_object(L2A_object):
         # perform spectral homogenization of image data #
         #################################################
 
-        SpH = SpectralHomogenizer(classifier_rootDir=CFG.path_spechomo_classif, logger=self.logger, CPUs=CFG.CPUs)
+        from ..processing.multiproc import is_mainprocess
+        SpH = SpectralHomogenizer(classifier_rootDir=CFG.path_spechomo_classif,
+                                  logger=self.logger,
+                                  CPUs=CFG.CPUs if is_mainprocess() else 1)
 
         if method == 'LI' or CFG.datasetid_spectral_ref is None:
             # linear interpolation (if intended by user or in case of custom spectral characteristics of target sensor)

gms_preprocessing/processing/multiproc.py

 # -*- coding: utf-8 -*-
 
-from multiprocessing import Pool
+from multiprocessing import Pool, current_process
 from itertools import chain
 
 from ..options.config import GMS_config as CFG
@@ -72,3 +72,9 @@ def imap_unordered(func, args, CPUs=None, flatten_output=False):
             return list(ch)
     else:
         return list(results)
+
+
+def is_mainprocess():
+    # type: () -> bool
+    """Return True if the current process is the main process and False if it is a multiprocessing child process."""
+    return current_process().name == 'MainProcess'