How to stream LLM tokens (without LangChain LLMs)¶
In this example we will stream tokens from the language model powering an agent. We'll be using OpenAI client library directly, without using LangChain chat models. We will also use a ReAct agent as an example.
Setup¶
First, let's install the required packages and set our API keys
import getpass
import os
def _set_env(var: str):
if not os.environ.get(var):
os.environ[var] = getpass.getpass(f"{var}: ")
_set_env("OPENAI_API_KEY")
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Define model, tools and graph¶
Define a node that will call OpenAI API¶
from openai import AsyncOpenAI
from langchain_core.language_models.chat_models import ChatGenerationChunk
from langchain_core.messages import AIMessageChunk
from langchain_core.runnables.config import (
ensure_config,
get_callback_manager_for_config,
)
openai_client = AsyncOpenAI()
# define tool schema for openai tool calling
tool = {
"type": "function",
"function": {
"name": "get_items",
"description": "Use this tool to look up which items are in the given place.",
"parameters": {
"type": "object",
"properties": {"place": {"type": "string"}},
"required": ["place"],
},
},
}
async def call_model(state, config=None):
config = ensure_config(config | {"tags": ["agent_llm"]})
callback_manager = get_callback_manager_for_config(config)
messages = state["messages"]
llm_run_manager = callback_manager.on_chat_model_start({}, [messages])[0]
response = await openai_client.chat.completions.create(
messages=messages, model="gpt-3.5-turbo", tools=[tool], stream=True
)
response_content = ""
role = None
tool_call_id = None
tool_call_function_name = None
tool_call_function_arguments = ""
async for chunk in response:
delta = chunk.choices[0].delta
if delta.role is not None:
role = delta.role
if delta.content:
response_content += delta.content
# note: we're wrapping the response in ChatGenerationChunk so that we can stream this back using stream_mode="messages"
chunk = ChatGenerationChunk(
message=AIMessageChunk(
content=delta.content,
)
)
llm_run_manager.on_llm_new_token(delta.content, chunk=chunk)
if delta.tool_calls:
# note: for simplicity we're only handling a single tool call here
if delta.tool_calls[0].function.name is not None:
tool_call_function_name = delta.tool_calls[0].function.name
tool_call_id = delta.tool_calls[0].id
# note: we're wrapping the tools calls in ChatGenerationChunk so that we can stream this back using stream_mode="messages"
tool_call_chunk = ChatGenerationChunk(
message=AIMessageChunk(
content="",
additional_kwargs={"tool_calls": [delta.tool_calls[0].dict()]},
)
)
llm_run_manager.on_llm_new_token("", chunk=tool_call_chunk)
tool_call_function_arguments += delta.tool_calls[0].function.arguments
if tool_call_function_name is not None:
tool_calls = [
{
"id": tool_call_id,
"function": {
"name": tool_call_function_name,
"arguments": tool_call_function_arguments,
},
"type": "function",
}
]
else:
tool_calls = None
response_message = {
"role": role,
"content": response_content,
"tool_calls": tool_calls,
}
return {"messages": [response_message]}
API Reference:
ChatGenerationChunk | AIMessageChunk | ensure_config | get_callback_manager_for_config
Define our tools and a tool-calling node¶
import json
async def get_items(place: str) -> str:
"""Use this tool to look up which items are in the given place."""
if "bed" in place: # For under the bed
return "socks, shoes and dust bunnies"
if "shelf" in place: # For 'shelf'
return "books, penciles and pictures"
else: # if the agent decides to ask about a different place
return "cat snacks"
# define mapping to look up functions when running tools
function_name_to_function = {"get_items": get_items}
async def call_tools(state):
messages = state["messages"]
tool_call = messages[-1]["tool_calls"][0]
function_name = tool_call["function"]["name"]
function_arguments = tool_call["function"]["arguments"]
arguments = json.loads(function_arguments)
function_response = await function_name_to_function[function_name](**arguments)
tool_message = {
"tool_call_id": tool_call["id"],
"role": "tool",
"name": function_name,
"content": function_response,
}
return {"messages": [tool_message]}
Define our graph¶
import operator
from typing import Annotated, Literal
from typing_extensions import TypedDict
from langgraph.graph import StateGraph, END, START
class State(TypedDict):
messages: Annotated[list, operator.add]
def should_continue(state) -> Literal["tools", END]:
messages = state["messages"]
last_message = messages[-1]
if last_message["tool_calls"]:
return "tools"
return END
workflow = StateGraph(State)
workflow.add_edge(START, "model")
workflow.add_node("model", call_model) # i.e. our "agent"
workflow.add_node("tools", call_tools)
workflow.add_conditional_edges("model", should_continue)
workflow.add_edge("tools", "model")
graph = workflow.compile()
Stream tokens¶
from langchain_core.messages import AIMessageChunk
first = True
async for msg, metadata in graph.astream(
{"messages": [{"role": "user", "content": "what's in the bedroom"}]},
stream_mode="messages",
):
if msg.content:
print(msg.content, end="|", flush=True)
if isinstance(msg, AIMessageChunk):
if first:
gathered = msg
first = False
else:
gathered = gathered + msg
if msg.tool_call_chunks:
print(gathered.tool_calls)
[{'name': 'get_items', 'args': {}, 'id': 'call_h7g3jsgeRXIOUiaEC0VtM4EI', 'type': 'tool_call'}]
[{'name': 'get_items', 'args': {}, 'id': 'call_h7g3jsgeRXIOUiaEC0VtM4EI', 'type': 'tool_call'}]
[{'name': 'get_items', 'args': {}, 'id': 'call_h7g3jsgeRXIOUiaEC0VtM4EI', 'type': 'tool_call'}]
[{'name': 'get_items', 'args': {'place': ''}, 'id': 'call_h7g3jsgeRXIOUiaEC0VtM4EI', 'type': 'tool_call'}]
[{'name': 'get_items', 'args': {'place': 'bed'}, 'id': 'call_h7g3jsgeRXIOUiaEC0VtM4EI', 'type': 'tool_call'}]
[{'name': 'get_items', 'args': {'place': 'bedroom'}, 'id': 'call_h7g3jsgeRXIOUiaEC0VtM4EI', 'type': 'tool_call'}]
[{'name': 'get_items', 'args': {'place': 'bedroom'}, 'id': 'call_h7g3jsgeRXIOUiaEC0VtM4EI', 'type': 'tool_call'}]
In| the| bedroom|,| you| have| socks|,| shoes|,| and| some| dust| b|unn|ies|.|
API Reference:
AIMessageChunk