[tune] replace self.config (#6313)

python/ray/tune/examples/pbt_example.py

@@ -81,6 +81,7 @@ class PBTBenchmarkExample(Trainable):
 
     def reset_config(self, new_config):
         self.lr = new_config["lr"]
+        self.config = new_config
         return True
 
 

python/ray/tune/trainable.py

@@ -396,7 +396,8 @@ class Trainable(object):
 
         This method is optional, but can be implemented to speed up algorithms
         such as PBT, and to allow performance optimizations such as running
-        experiments with reuse_actors=True.
+        experiments with reuse_actors=True. Note that self.config need to
+        be updated to reflect the latest parameter information in Ray logs.
 
         Args:
             new_config (dir): Updated hyperparameter configuration