Async API

LangChain provides async support by leveraging the asyncio library.

Async support is built into all Runnable objects (the building block of LangChain Expression Language (LCEL) by default. Using LCEL is preferred to using Chains. Head to Interface for more on the Runnable interface.

import asyncio
import time

from langchain.chains import LLMChain
from langchain.llms import OpenAI
from langchain.prompts import PromptTemplate


def generate_serially():
    llm = OpenAI(temperature=0.9)
    prompt = PromptTemplate(
        input_variables=["product"],
        template="What is a good name for a company that makes {product}?",
    )
    chain = LLMChain(llm=llm, prompt=prompt)
    for _ in range(5):
        resp = chain.run(product="toothpaste")
        print(resp)


async def async_generate(chain):
    resp = await chain.arun(product="toothpaste")
    print(resp)


async def generate_concurrently():
    llm = OpenAI(temperature=0.9)
    prompt = PromptTemplate(
        input_variables=["product"],
        template="What is a good name for a company that makes {product}?",
    )
    chain = LLMChain(llm=llm, prompt=prompt)
    tasks = [async_generate(chain) for _ in range(5)]
    await asyncio.gather(*tasks)


s = time.perf_counter()
# If running this outside of Jupyter, use asyncio.run(generate_concurrently())
await generate_concurrently()
elapsed = time.perf_counter() - s
print("\033[1m" + f"Concurrent executed in {elapsed:0.2f} seconds." + "\033[0m")

s = time.perf_counter()
generate_serially()
elapsed = time.perf_counter() - s
print("\033[1m" + f"Serial executed in {elapsed:0.2f} seconds." + "\033[0m")

BrightSmile Toothpaste Company


BrightSmile Toothpaste Co.


BrightSmile Toothpaste


Gleaming Smile Inc.


SparkleSmile Toothpaste
Concurrent executed in 1.54 seconds.


BrightSmile Toothpaste Co.


MintyFresh Toothpaste Co.


SparkleSmile Toothpaste.


Pearly Whites Toothpaste Co.


BrightSmile Toothpaste.
Serial executed in 6.38 seconds.