Fix memory leak in base_class.py (#1908)

* Fix memory leak in base_class.py

Loading the data return value is not necessary since it is unused. Loading the data causes a memory leak through the ep_info_buffer variable. I found this while loading a PPO learner from storage on a multi-GPU system since the ep_info_buffer is loaded to the memory location it was on while it was saved to disk, instead of the target loading location, and is then not cleaned up.

* Update changelog.rst

* Update changelog

---------

Co-authored-by: Antonin RAFFIN <antonin.raffin@ensta.org>

docs/misc/changelog.rst

@@ -3,7 +3,7 @@
 Changelog
 ==========
 
-Release 2.4.0a0 (WIP)
+Release 2.4.0a1 (WIP)
 --------------------------
 
 Breaking Changes:
@@ -14,6 +14,8 @@ New Features:
 
 Bug Fixes:
 ^^^^^^^^^^
+- Fixed memory leak when loading learner from storage, ``set_parameters()`` does not try to load the object data anymore
+  and only loads the PyTorch parameters (@peteole)
 - Cast type in compute gae method to avoid error when using torch compile (@amjames)
 
 `SB3-Contrib`_
@@ -30,7 +32,7 @@ Deprecations:
 
 Others:
 ^^^^^^^
-- Fix various typos (@cschindlbeck)
+- Fixed various typos (@cschindlbeck)
 
 Bug Fixes:
 ^^^^^^^^^^
@@ -1659,4 +1661,4 @@ And all the contributors:
 @anand-bala @hughperkins @sidney-tio @AlexPasqua @dominicgkerr @Akhilez @Rocamonde @tobirohrer @ZikangXiong @ReHoss
 @DavyMorgan @luizapozzobon @Bonifatius94 @theSquaredError @harveybellini @DavyMorgan @FieteO @jonasreiher @npit @WeberSamuel @troiganto
 @lutogniew @lbergmann1 @lukashass @BertrandDecoster @pseudo-rnd-thoughts @stefanbschneider @kyle-he @PatrickHelm @corentinlger
-@marekm4 @stagoverflow @rushitnshah @markscsmith @NickLucche @cschindlbeck
+@marekm4 @stagoverflow @rushitnshah @markscsmith @NickLucche @cschindlbeck @peteole

stable_baselines3/common/base_class.py

@@ -592,7 +592,7 @@ def set_parameters(
         if isinstance(load_path_or_dict, dict):
             params = load_path_or_dict
         else:
-            _, params, _ = load_from_zip_file(load_path_or_dict, device=device)
+            _, params, _ = load_from_zip_file(load_path_or_dict, device=device, load_data=False)
 
         # Keep track which objects were updated.
         # `_get_torch_save_params` returns [params, other_pytorch_variables].

stable_baselines3/version.txt

@@ -1 +1 @@
-2.4.0a0
+2.4.0a1