Resolve "release v1.4.0"

Closes #317 (closed)

mlair/run_modules/pre_processing.py

@@ -245,7 +245,7 @@ class PreProcessing(RunEnvironment):
 
         max_process = self.data_store.get("max_number_multiprocessing")
         n_process = min([psutil.cpu_count(logical=False), len(set_stations), max_process])  # use only physical cpus
-        if n_process > 1 and use_multiprocessing:  # parallel solution
+        if n_process > 1 and use_multiprocessing is True:  # parallel solution
             logging.info("use parallel validate station approach")
             pool = multiprocessing.Pool(n_process)
             logging.info(f"running {getattr(pool, '_processes')} processes in parallel")