Use shallow copy on runnable locals (#10825)

- deep copy prevents storing complex objects in locals

libs/langchain/langchain/schema/runnable/_locals.py

@@ -48,10 +48,10 @@ class PutLocalVar(RunnablePassthrough):
                 "therefore always receive a non-null config."
             )
         if isinstance(self.key, str):
-            if self.key not in config["_locals"] or replace:
-                config["_locals"][self.key] = input
+            if self.key not in config["locals"] or replace:
+                config["locals"][self.key] = input
             else:
-                config["_locals"][self.key] += input
+                config["locals"][self.key] += input
         elif isinstance(self.key, Mapping):
             if not isinstance(input, Mapping):
                 raise TypeError(
@@ -59,10 +59,10 @@ class PutLocalVar(RunnablePassthrough):
                     f"input is expected to be of type Mapping when key is Mapping."
                 )
             for input_key, put_key in self.key.items():
-                if put_key not in config["_locals"] or replace:
-                    config["_locals"][put_key] = input[input_key]
+                if put_key not in config["locals"] or replace:
+                    config["locals"][put_key] = input[input_key]
                 else:
-                    config["_locals"][put_key] += input[input_key]
+                    config["locals"][put_key] += input[input_key]
         else:
             raise TypeError(
                 f"`key` should be a string or Mapping[str, str], received type "
@@ -127,11 +127,11 @@ class GetLocalVar(
     ) -> Union[Output, Dict[str, Union[Input, Output]]]:
         if self.passthrough_key:
             return {
-                self.key: config["_locals"][self.key],
+                self.key: config["locals"][self.key],
                 self.passthrough_key: input,
             }
         else:
-            return config["_locals"][self.key]
+            return config["locals"][self.key]
 
     async def _aget(
         self,

libs/langchain/langchain/schema/runnable/base.py

@@ -1628,7 +1628,7 @@ class RunnableMap(Serializable, Runnable[Input, Dict[str, Any]]):
                         # mark each step as a child run
                         patch_config(
                             config,
-                            deep_copy_locals=True,
+                            copy_locals=True,
                             callbacks=run_manager.get_child(f"map:key:{key}"),
                         ),
                     )
@@ -2111,7 +2111,7 @@ class RunnableBinding(Serializable, Runnable[Input, Output]):
             )
         else:
             configs = [
-                patch_config(self._merge_config(config), deep_copy_locals=True)
+                patch_config(self._merge_config(config), copy_locals=True)
                 for _ in range(len(inputs))
             ]
         return self.bound.batch(
@@ -2135,7 +2135,7 @@ class RunnableBinding(Serializable, Runnable[Input, Output]):
             )
         else:
             configs = [
-                patch_config(self._merge_config(config), deep_copy_locals=True)
+                patch_config(self._merge_config(config), copy_locals=True)
                 for _ in range(len(inputs))
             ]
         return await self.bound.abatch(

libs/langchain/langchain/schema/runnable/config.py

@@ -2,7 +2,6 @@ from __future__ import annotations
 
 from concurrent.futures import Executor, ThreadPoolExecutor
 from contextlib import contextmanager
-from copy import deepcopy
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -13,6 +12,7 @@ from typing import (
     List,
     Optional,
     Union,
+    cast,
 )
 
 from typing_extensions import TypedDict
@@ -60,9 +60,11 @@ class RunnableConfig(TypedDict, total=False):
     Name for the tracer run for this call. Defaults to the name of the class.
     """
 
-    _locals: Dict[str, Any]
+    locals: Dict[str, Any]
     """
-    Local variables
+    Variables scoped to this call and any sub-calls. Usually used with
+    GetLocalVar() and PutLocalVar(). Care should be taken when placing mutable
+    objects in locals, as they will be shared between parallel sub-calls.
     """
 
     max_concurrency: Optional[int]
@@ -82,11 +84,13 @@ def ensure_config(config: Optional[RunnableConfig] = None) -> RunnableConfig:
         tags=[],
         metadata={},
         callbacks=None,
-        _locals={},
+        locals={},
         recursion_limit=10,
     )
     if config is not None:
-        empty.update(config)
+        empty.update(
+            cast(RunnableConfig, {k: v for k, v in config.items() if v is not None})
+        )
     return empty
 
 
@@ -108,22 +112,22 @@ def get_config_list(
     return (
         list(map(ensure_config, config))
         if isinstance(config, list)
-        else [patch_config(config, deep_copy_locals=True) for _ in range(length)]
+        else [patch_config(config, copy_locals=True) for _ in range(length)]
     )
 
 
 def patch_config(
     config: Optional[RunnableConfig],
     *,
-    deep_copy_locals: bool = False,
+    copy_locals: bool = False,
     callbacks: Optional[BaseCallbackManager] = None,
     recursion_limit: Optional[int] = None,
     max_concurrency: Optional[int] = None,
     run_name: Optional[str] = None,
 ) -> RunnableConfig:
     config = ensure_config(config)
-    if deep_copy_locals:
-        config["_locals"] = deepcopy(config["_locals"])
+    if copy_locals:
+        config["locals"] = config["locals"].copy()
     if callbacks is not None:
         # If we're replacing callbacks we need to unset run_name
         # As that should apply only to the same run as the original callbacks

libs/langchain/tests/unit_tests/schema/runnable/test_runnable.py

@@ -215,7 +215,7 @@ async def test_with_config(mocker: MockerFixture) -> None:
                 metadata={"key": "value"},
                 tags=["c"],
                 callbacks=None,
-                _locals={},
+                locals={},
                 recursion_limit=5,
             ),
         ),
@@ -225,7 +225,7 @@ async def test_with_config(mocker: MockerFixture) -> None:
                 metadata={"key": "value"},
                 tags=["c"],
                 callbacks=None,
-                _locals={},
+                locals={},
                 recursion_limit=5,
             ),
         ),
@@ -296,7 +296,7 @@ async def test_default_method_implementations(mocker: MockerFixture) -> None:
                 metadata={"key": "value"},
                 tags=[],
                 callbacks=None,
-                _locals={},
+                locals={},
                 recursion_limit=10,
             ),
         ),
@@ -306,7 +306,7 @@ async def test_default_method_implementations(mocker: MockerFixture) -> None:
                 metadata={"key": "value"},
                 tags=[],
                 callbacks=None,
-                _locals={},
+                locals={},
                 recursion_limit=10,
             ),
         ),