Update simple_cerebros_random_search.py

Garbage collecting to cure RAM pressure accumulation: Added garbage collection and ensure a clean keras back-end state before starting a new model.

Author: david-thrower

cerebros/simplecerebrosrandomsearch/simple_cerebros_random_search.py

@@ -13,6 +13,8 @@
 # from cmdutil.cmdutil import run_command
 from multiprocessing import Process, Lock
 import os
+from gc import collect
+
 
 # import optuna
 # from optuna.pruners import BasePruner
@@ -480,6 +482,8 @@ def run_moity_permutations(self, spec, subtrial_number, lock):
             model_graph_file=model_graph_file,
             train_data_dtype=self.train_data_dtype
             )
+        tf.keras.backend.clear_session()
+        collect()
         nnf.materialize()
         nnf.compile_neural_network()
         neural_network = nnf.materialized_neural_network
@@ -515,7 +519,11 @@ def run_moity_permutations(self, spec, subtrial_number, lock):
                         index=False,
                         header=self.needs_oracle_header,
                         mode='a')
+        
         self.needs_oracle_header = False
+        neural_network = None
+        tf.keras.backend.clear_session()
+        collect()
         return 0
 
     def run_random_search(self):