Use a shared executor for all parallel calls

libs/langchain/langchain/schema/runnable/__init__.py

@@ -7,11 +7,12 @@ from langchain.schema.runnable.base import (
     RunnableSequence,
     RunnableWithFallbacks,
 )
-from langchain.schema.runnable.config import RunnableConfig
+from langchain.schema.runnable.config import RunnableConfig, patch_config
 from langchain.schema.runnable.passthrough import RunnablePassthrough
 from langchain.schema.runnable.router import RouterInput, RouterRunnable
 
 __all__ = [
+    "patch_config",
     "GetLocalVar",
     "PutLocalVar",
     "RouterInput",

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

@@ -1,11 +1,9 @@
 from __future__ import annotations
 
 import asyncio
-import copy
 import threading
 from abc import ABC, abstractmethod
-from concurrent.futures import FIRST_COMPLETED, ThreadPoolExecutor, wait
-from copy import deepcopy
+from concurrent.futures import FIRST_COMPLETED, wait
 from functools import partial
 from itertools import tee
 from typing import (
@@ -43,6 +41,7 @@ from langchain.schema.runnable.config import (
     ensure_config,
     get_async_callback_manager_for_config,
     get_callback_manager_for_config,
+    get_executor_for_config,
     patch_config,
 )
 from langchain.schema.runnable.utils import (
@@ -104,8 +103,6 @@ class Runnable(Generic[Input, Output], ABC):
         self,
         inputs: List[Input],
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
-        *,
-        max_concurrency: Optional[int] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
         """
@@ -118,15 +115,19 @@ class Runnable(Generic[Input, Output], ABC):
         if len(inputs) == 1:
             return [self.invoke(inputs[0], configs[0], **kwargs)]
 
-        with ThreadPoolExecutor(max_workers=max_concurrency) as executor:
-            return list(executor.map(partial(self.invoke, **kwargs), inputs, configs))
+        with get_executor_for_config(configs[0]) as executor:
+            return list(
+                executor.map(
+                    partial(self.invoke, **kwargs),
+                    inputs,
+                    (patch_config(c, executor=executor) for c in configs),
+                )
+            )
 
     async def abatch(
         self,
         inputs: List[Input],
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
-        *,
-        max_concurrency: Optional[int] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
         """
@@ -136,7 +137,7 @@ class Runnable(Generic[Input, Output], ABC):
         configs = self._get_config_list(config, len(inputs))
         coros = map(partial(self.ainvoke, **kwargs), inputs, configs)
 
-        return await gather_with_concurrency(max_concurrency, *coros)
+        return await gather_with_concurrency(configs[0].get("max_concurrency"), *coros)
 
     def stream(
         self,
@@ -246,7 +247,7 @@ class Runnable(Generic[Input, Output], ABC):
         return (
             list(map(ensure_config, config))
             if isinstance(config, list)
-            else [deepcopy(ensure_config(config)) for _ in range(length)]
+            else [patch_config(config, deep_copy_locals=True) for _ in range(length)]
         )
 
     def _call_with_config(
@@ -527,7 +528,7 @@ class RunnableWithFallbacks(Serializable, Runnable[Input, Output]):
             try:
                 output = runnable.invoke(
                     input,
-                    patch_config(config, run_manager.get_child()),
+                    patch_config(config, callbacks=run_manager.get_child()),
                 )
             except self.exceptions_to_handle as e:
                 if first_error is None:
@@ -560,7 +561,7 @@ class RunnableWithFallbacks(Serializable, Runnable[Input, Output]):
             try:
                 output = await runnable.ainvoke(
                     input,
-                    patch_config(config, run_manager.get_child()),
+                    patch_config(config, callbacks=run_manager.get_child()),
                 )
             except self.exceptions_to_handle as e:
                 if first_error is None:
@@ -580,8 +581,6 @@ class RunnableWithFallbacks(Serializable, Runnable[Input, Output]):
         self,
         inputs: List[Input],
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
-        *,
-        max_concurrency: Optional[int] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
         from langchain.callbacks.manager import CallbackManager
@@ -615,10 +614,9 @@ class RunnableWithFallbacks(Serializable, Runnable[Input, Output]):
                     inputs,
                     [
                         # each step a child run of the corresponding root run
-                        patch_config(config, rm.get_child())
+                        patch_config(config, callbacks=rm.get_child())
                         for rm, config in zip(run_managers, configs)
                     ],
-                    max_concurrency=max_concurrency,
                 )
             except self.exceptions_to_handle as e:
                 if first_error is None:
@@ -641,14 +639,9 @@ class RunnableWithFallbacks(Serializable, Runnable[Input, Output]):
         self,
         inputs: List[Input],
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
-        *,
-        max_concurrency: Optional[int] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
-        from langchain.callbacks.manager import (
-            AsyncCallbackManager,
-            AsyncCallbackManagerForChainRun,
-        )
+        from langchain.callbacks.manager import AsyncCallbackManager
 
         # setup callbacks
         configs = self._get_config_list(config, len(inputs))
@@ -679,10 +672,9 @@ class RunnableWithFallbacks(Serializable, Runnable[Input, Output]):
                     inputs,
                     [
                         # each step a child run of the corresponding root run
-                        patch_config(config, rm.get_child())
+                        patch_config(config, callbacks=rm.get_child())
                         for rm, config in zip(run_managers, configs)
                     ],
-                    max_concurrency=max_concurrency,
                 )
             except self.exceptions_to_handle as e:
                 if first_error is None:
@@ -782,7 +774,7 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
                 input = step.invoke(
                     input,
                     # mark each step as a child run
-                    patch_config(config, run_manager.get_child()),
+                    patch_config(config, callbacks=run_manager.get_child()),
                 )
         # finish the root run
         except (KeyboardInterrupt, Exception) as e:
@@ -810,7 +802,7 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
                 input = await step.ainvoke(
                     input,
                     # mark each step as a child run
-                    patch_config(config, run_manager.get_child()),
+                    patch_config(config, callbacks=run_manager.get_child()),
                 )
         # finish the root run
         except (KeyboardInterrupt, Exception) as e:
@@ -824,8 +816,6 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
         self,
         inputs: List[Input],
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
-        *,
-        max_concurrency: Optional[int] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
         from langchain.callbacks.manager import CallbackManager
@@ -852,15 +842,17 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
 
         # invoke
         try:
+            with get_executor_for_config(configs[0]) as executor:
                 for step in self.steps:
                     inputs = step.batch(
                         inputs,
                         [
                             # each step a child run of the corresponding root run
-                        patch_config(config, rm.get_child())
+                            patch_config(
+                                config, callbacks=rm.get_child(), executor=executor
+                            )
                             for rm, config in zip(run_managers, configs)
                         ],
-                    max_concurrency=max_concurrency,
                     )
         # finish the root runs
         except (KeyboardInterrupt, Exception) as e:
@@ -876,8 +868,6 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
         self,
         inputs: List[Input],
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
-        *,
-        max_concurrency: Optional[int] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
         from langchain.callbacks.manager import (
@@ -914,10 +904,9 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
                     inputs,
                     [
                         # each step a child run of the corresponding root run
-                        patch_config(config, rm.get_child())
+                        patch_config(config, callbacks=rm.get_child())
                         for rm, config in zip(run_managers, configs)
                     ],
-                    max_concurrency=max_concurrency,
                 )
         # finish the root runs
         except (KeyboardInterrupt, Exception) as e:
@@ -956,7 +945,7 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
                 input = step.invoke(
                     input,
                     # mark each step as a child run
-                    patch_config(config, run_manager.get_child()),
+                    patch_config(config, callbacks=run_manager.get_child()),
                 )
         except (KeyboardInterrupt, Exception) as e:
             run_manager.on_chain_error(e)
@@ -968,12 +957,13 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
         try:
             # stream the first of the last steps with non-streaming input
             final_pipeline = steps[streaming_start_index].stream(
-                input, patch_config(config, run_manager.get_child())
+                input, patch_config(config, callbacks=run_manager.get_child())
             )
             # stream the rest of the last steps with streaming input
             for step in steps[streaming_start_index + 1 :]:
                 final_pipeline = step.transform(
-                    final_pipeline, patch_config(config, run_manager.get_child())
+                    final_pipeline,
+                    patch_config(config, callbacks=run_manager.get_child()),
                 )
             for output in final_pipeline:
                 yield output
@@ -1022,7 +1012,7 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
                 input = await step.ainvoke(
                     input,
                     # mark each step as a child run
-                    patch_config(config, run_manager.get_child()),
+                    patch_config(config, callbacks=run_manager.get_child()),
                 )
         except (KeyboardInterrupt, Exception) as e:
             await run_manager.on_chain_error(e)
@@ -1034,12 +1024,13 @@ class RunnableSequence(Serializable, Runnable[Input, Output]):
         try:
             # stream the first of the last steps with non-streaming input
             final_pipeline = steps[streaming_start_index].astream(
-                input, patch_config(config, run_manager.get_child())
+                input, patch_config(config, callbacks=run_manager.get_child())
             )
             # stream the rest of the last steps with streaming input
             for step in steps[streaming_start_index + 1 :]:
                 final_pipeline = step.atransform(
-                    final_pipeline, patch_config(config, run_manager.get_child())
+                    final_pipeline,
+                    patch_config(config, callbacks=run_manager.get_child()),
                 )
             async for output in final_pipeline:
                 yield output
@@ -1068,7 +1059,7 @@ class RunnableMapChunk(Dict[str, Any]):
     """
 
     def __add__(self, other: RunnableMapChunk) -> RunnableMapChunk:
-        chunk = copy.deepcopy(self)
+        chunk = self.copy()
         for key in other:
             if key not in chunk or chunk[key] is None:
                 chunk[key] = other[key]
@@ -1076,6 +1067,15 @@ class RunnableMapChunk(Dict[str, Any]):
                 chunk[key] += other[key]
         return chunk
 
+    def __radd__(self, other: RunnableMapChunk) -> RunnableMapChunk:
+        chunk = RunnableMapChunk(other)
+        for key in self:
+            if key not in chunk or chunk[key] is None:
+                chunk[key] = self[key]
+            elif self[key] is not None:
+                chunk[key] += self[key]
+        return chunk
+
 
 class RunnableMap(Serializable, Runnable[Input, Dict[str, Any]]):
     """
@@ -1132,13 +1132,18 @@ class RunnableMap(Serializable, Runnable[Input, Dict[str, Any]]):
         try:
             # copy to avoid issues from the caller mutating the steps during invoke()
             steps = dict(self.steps)
-            with ThreadPoolExecutor() as executor:
+            with get_executor_for_config(config) as executor:
                 futures = [
                     executor.submit(
                         step.invoke,
                         input,
                         # mark each step as a child run
-                        patch_config(deepcopy(config), run_manager.get_child()),
+                        patch_config(
+                            config,
+                            deep_copy_locals=True,
+                            callbacks=run_manager.get_child(),
+                            executor=executor,
+                        ),
                     )
                     for step in steps.values()
                 ]
@@ -1172,7 +1177,7 @@ class RunnableMap(Serializable, Runnable[Input, Dict[str, Any]]):
                     step.ainvoke(
                         input,
                         # mark each step as a child run
-                        patch_config(config, run_manager.get_child()),
+                        patch_config(config, callbacks=run_manager.get_child()),
                     )
                     for step in steps.values()
                 )
@@ -1197,14 +1202,16 @@ class RunnableMap(Serializable, Runnable[Input, Dict[str, Any]]):
         # Each step gets a copy of the input iterator,
         # which is consumed in parallel in a separate thread.
         input_copies = list(safetee(input, len(steps), lock=threading.Lock()))
-        with ThreadPoolExecutor() as executor:
+        with get_executor_for_config(config) as executor:
             # Create the transform() generator for each step
             named_generators = [
                 (
                     name,
                     step.transform(
                         input_copies.pop(),
-                        patch_config(config, run_manager.get_child()),
+                        patch_config(
+                            config, callbacks=run_manager.get_child(), executor=executor
+                        ),
                     ),
                 )
                 for name, step in steps.items()
@@ -1265,7 +1272,8 @@ class RunnableMap(Serializable, Runnable[Input, Dict[str, Any]]):
             (
                 name,
                 step.atransform(
-                    input_copies.pop(), patch_config(config, run_manager.get_child())
+                    input_copies.pop(),
+                    patch_config(config, callbacks=run_manager.get_child()),
                 ),
             )
             for name, step in steps.items()
@@ -1393,25 +1401,17 @@ class RunnableBinding(Serializable, Runnable[Input, Output]):
         self,
         inputs: List[Input],
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
-        *,
-        max_concurrency: Optional[int] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
-        return self.bound.batch(
-            inputs, config, max_concurrency=max_concurrency, **{**self.kwargs, **kwargs}
-        )
+        return self.bound.batch(inputs, config, **{**self.kwargs, **kwargs})
 
     async def abatch(
         self,
         inputs: List[Input],
         config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
-        *,
-        max_concurrency: Optional[int] = None,
         **kwargs: Optional[Any],
     ) -> List[Output]:
-        return await self.bound.abatch(
-            inputs, config, max_concurrency=max_concurrency, **{**self.kwargs, **kwargs}
-        )
+        return await self.bound.abatch(inputs, config, **{**self.kwargs, **kwargs})
 
     def stream(
         self,

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

@@ -1,6 +1,9 @@
 from __future__ import annotations
+from concurrent.futures import Executor, ThreadPoolExecutor
+from contextlib import contextmanager
+from copy import deepcopy
 
-from typing import Any, Dict, List, Optional, TypedDict
+from typing import Any, Dict, Generator, List, Optional, TypedDict
 
 from langchain.callbacks.base import BaseCallbackManager, Callbacks
 from langchain.callbacks.manager import AsyncCallbackManager, CallbackManager
@@ -32,20 +35,44 @@ class RunnableConfig(TypedDict, total=False):
     Local variables
     """
 
+    max_concurrency: Optional[int]
+    """
+    Maximum number of parallel calls to make. If not provided, defaults to ThreadPoolExecutor's default. This is ignored if an executor is provided.
+    """
+
+    executor: Executor
+    """
+    Externally-managed executor to use for parallel calls. If not provided, a new
+    ThreadPoolExecutor will be created.
+    """
+
 
 def ensure_config(config: Optional[RunnableConfig]) -> RunnableConfig:
-    empty = RunnableConfig(tags=[], metadata={}, callbacks=None, _locals={})
+    empty = RunnableConfig(
+        tags=[],
+        metadata={},
+        callbacks=None,
+        _locals={},
+    )
     if config is not None:
         empty.update(config)
     return empty
 
 
 def patch_config(
-    config: RunnableConfig,
-    callbacks: BaseCallbackManager,
+    config: Optional[RunnableConfig],
+    *,
+    deep_copy_locals: bool = False,
+    callbacks: Optional[BaseCallbackManager] = None,
+    executor: Optional[Executor] = None,
 ) -> RunnableConfig:
-    config = config.copy()
+    config = ensure_config(config)
+    if deep_copy_locals:
+        config["_locals"] = deepcopy(config["_locals"])
+    if callbacks is not None:
         config["callbacks"] = callbacks
+    if executor is not None:
+        config["executor"] = executor
     return config
 
 
@@ -65,3 +92,12 @@ def get_async_callback_manager_for_config(
         inheritable_tags=config.get("tags"),
         inheritable_metadata=config.get("metadata"),
     )
+
+
+@contextmanager
+def get_executor_for_config(config: RunnableConfig) -> Generator[Executor, None, None]:
+    if config.get("executor"):
+        yield config["executor"]
+    else:
+        with ThreadPoolExecutor(max_workers=config.get("max_concurrency")) as executor:
+            yield executor

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

@@ -131,26 +131,25 @@ async def test_default_method_implementations(mocker: MockerFixture) -> None:
     assert fake.batch(
         ["hello", "wooorld"], [dict(tags=["a-tag"]), dict(metadata={"key": "value"})]
     ) == [5, 7]
-    assert spy.call_args_list == [
-        mocker.call(
-            "hello", dict(tags=["a-tag"], metadata={}, callbacks=None, _locals={})
-        ),
-        mocker.call(
-            "wooorld",
-            dict(metadata={"key": "value"}, tags=[], callbacks=None, _locals={}),
-        ),
-    ]
+
+    assert len(spy.call_args_list) == 2
+    for i, call in enumerate(spy.call_args_list):
+        assert call.args[0] == ("hello" if i == 0 else "wooorld")
+        if i == 0:
+            assert call.args[1].get("tags") == ["a-tag"]
+            assert call.args[1].get("metadata") == {}
+        else:
+            assert call.args[1].get("tags") == []
+            assert call.args[1].get("metadata") == {"key": "value"}
+
     spy.reset_mock()
 
     assert fake.batch(["hello", "wooorld"], dict(tags=["a-tag"])) == [5, 7]
-    assert spy.call_args_list == [
-        mocker.call(
-            "hello", dict(tags=["a-tag"], metadata={}, callbacks=None, _locals={})
-        ),
-        mocker.call(
-            "wooorld", dict(tags=["a-tag"], metadata={}, callbacks=None, _locals={})
-        ),
-    ]
+    assert len(spy.call_args_list) == 2
+    for i, call in enumerate(spy.call_args_list):
+        assert call.args[0] == ("hello" if i == 0 else "wooorld")
+        assert call.args[1].get("tags") == ["a-tag"]
+        assert call.args[1].get("metadata") == {}
     spy.reset_mock()
 
     assert await fake.ainvoke("hello", config={"callbacks": []}) == 5
@@ -172,11 +171,21 @@ async def test_default_method_implementations(mocker: MockerFixture) -> None:
     assert spy.call_args_list == [
         mocker.call(
             "hello",
-            dict(metadata={"key": "value"}, tags=[], callbacks=None, _locals={}),
+            dict(
+                metadata={"key": "value"},
+                tags=[],
+                callbacks=None,
+                _locals={},
+            ),
         ),
         mocker.call(
             "wooorld",
-            dict(metadata={"key": "value"}, tags=[], callbacks=None, _locals={}),
+            dict(
+                metadata={"key": "value"},
+                tags=[],
+                callbacks=None,
+                _locals={},
+            ),
         ),
     ]