diff --git a/mlair/data_handler/default_data_handler.py b/mlair/data_handler/default_data_handler.py
index 799dcc45f66cd0519d172a62d15f911823907816..291bbc6616314db61282c380a6b3e105d8b6248a 100644
--- a/mlair/data_handler/default_data_handler.py
+++ b/mlair/data_handler/default_data_handler.py
@@ -256,6 +256,7 @@ class DefaultDataHandler(AbstractDataHandler):
         if multiprocessing.cpu_count() > 1:  # parallel solution
             logging.info("use parallel transformation approach")
             pool = multiprocessing.Pool()
+            logging.info(f"running {getattr(pool, '_processes')} processes in parallel")
             output = [
                 pool.apply_async(f_proc, args=(cls.data_handler_transformation, station), kwds=sp_keys)
                 for station in set_stations]
diff --git a/mlair/run_modules/pre_processing.py b/mlair/run_modules/pre_processing.py
index 8be5870a3d1945c18e0f27278dc30af0c7c61139..a7c774215a802142260b0c1b27d9a905a30f337e 100644
--- a/mlair/run_modules/pre_processing.py
+++ b/mlair/run_modules/pre_processing.py
@@ -264,6 +264,7 @@ class PreProcessing(RunEnvironment):
         if multiprocessing.cpu_count() > 1:  # parallel solution
             logging.info("use parallel validate station approach")
             pool = multiprocessing.Pool()
+            logging.info(f"running {getattr(pool, '_processes')} processes in parallel")
             output = [
                 pool.apply_async(f_proc, args=(data_handler, station, set_name, store_processed_data), kwds=kwargs)
                 for station in set_stations]