Async Processing OpenAI using asyncio and Instructor with Python¶

Today, I will introduce you to various approaches for using asyncio in Python. We will apply this to batch process data using instructor and learn how to use asyncio.gather and asyncio.as_completed for concurrent data processing. Additionally, we will explore how to limit the number of concurrent requests to a server using asyncio.Semaphore.

We will start by defining an async function that calls openai to extract data, and then examine four different ways to execute it. We will discuss the pros and cons of each approach and analyze the results of running them on a small batch.

Understanding asyncio¶

asyncio is a Python library that enables writing concurrent code using the async/await syntax. It is particularly useful for IO-bound and structured network code. If you are familiar with OpenAI's SDK, you might have encountered two classes: OpenAI() and AsyncOpenAI(). Today, we will be using the AsyncOpenAI() class, which processes data asynchronously.

By utilizing these tools in web applications or bulk processing, we can significantly improve performance by handling multiple requests concurrently instead of sequentially.

Understanding async and await¶

We will be using the async and await keywords to define asynchronous functions. The async keyword is used to define a function that returns a coroutine object. The await keyword is used to wait for the result of a coroutine object.

If you want to understand the deeper details of asyncio, I recommend reading this article by Real Python.

Understanding gather vs as_completed¶

In this post we'll show two ways to run tasks concurrently: asyncio.gather and asyncio.as_completed. The gather method is used to run multiple tasks concurrently and return the results as a list. The as_completed returns a iterable is used to run multiple tasks concurrently and return the results as they complete. Another great resource on the differences between the two can be found here.

Example: Batch Processing¶

In this example, we will demonstrate how to use asyncio for async processing tasks, specifically for extracting and processing data concurrently. The script will extract data from a list of texts and process it concurrently using asyncio.

import instructor
from pydantic import BaseModel
from openai import AsyncOpenAI

# Enables `response_model` in `create` method
client = instructor.apatch(AsyncOpenAI())  # (1)!


class Person(BaseModel):
    name: str
    age: int


async def extract_person(text: str) -> Person:
    return await client.chat.completions.create(  # (2)!
        model="gpt-3.5-turbo",
        messages=[
            {"role": "user", "content": text},
        ],
        response_model=Person,
    )

1. We use instructor.apatch to patch the create method of AsyncOpenAI to accept a response_model argument. This is because the create method of AsyncOpenAI does not accept a response_model argument without this patch.
2. We use await here to wait for the response from the server before we return the result. This is because create returns a coroutine object, not the result of the coroutine.

Notice that now there are async and await keywords in the function definition. This is because we're using the asyncio library to run the function concurrently. Now let's define a batch of texts to process.

dataset = [
    "My name is John and I am 20 years old",
    "My name is Mary and I am 21 years old",
    "My name is Bob and I am 22 years old",
    "My name is Alice and I am 23 years old",
    "My name is Jane and I am 24 years old",
    "My name is Joe and I am 25 years old",
    "My name is Jill and I am 26 years old",
]

for loop: Running tasks sequentially.¶

persons = []
for text in dataset:
    person = await extract_person(text)
    persons.append(person)

Even though there is an await keyword, we still have to wait for each task to finish before starting the next one. This is because we're using a for loop to iterate over the dataset. This method, which uses a for loop, will be the slowest among the four methods discussed today.

asyncio.gather: Running tasks concurrently.¶

async def gather():
    tasks_get_persons = [extract_person(text) for text in dataset]
    all_persons = await asyncio.gather(*tasks_get_persons)  # (1)!

1. We use await here to wait for all the tasks to finish before assigning the result to all_persons. This is because asyncio.gather returns a coroutine object, not the result of the coroutine. Alternatively, we can use asyncio.as_completed to achieve the same result.

Using asyncio.gather allows us to return all the results at once. It is an effective way to speed up our code, but it's not the only way. Particularly, if we have a large dataset, we might not want to wait for everything to finish before starting to process the results. This is where asyncio.as_completed comes into play.

asyncio.as_completed: Handling tasks as they complete.¶

async def as_completed():
    all_persons = []
    tasks_get_persons = [extract_person(text) for text in dataset]
    for person in asyncio.as_completed(tasks_get_persons):
        all_persons.append(await person)  # (1)!

1. We use await here to wait for each task to complete before appending it to the list. This is because as_completed returns a coroutine object, not the result of the coroutine. Alternatively, we can use asyncio.gather to achieve the same result.

This method is a great way to handle large datasets. We can start processing the results as they come in, especially if we are streaming data back to a client.

However, these methods aim to complete as many tasks as possible as quickly as possible. This can be problematic if we want to be considerate to the server we're making requests to. This is where rate limiting comes into play. While there are libraries available to assist with rate limiting, for our initial defense, we will use a semaphore to limit the number of concurrent requests we make.

Rate-Limited Gather: Using semaphores to limit concurrency.¶

sem = asyncio.Semaphore(2)


async def rate_limited_extract_person(text: str, sem: Semaphore) -> Person:
    async with sem:  # (1)!
        return await extract_person(text)


async def rate_limited_gather(sem: Semaphore):
    tasks_get_persons = [rate_limited_extract_person(text, sem) for text in dataset]
    resp = await asyncio.gather(*tasks_get_persons)

1. We use a semaphore to limit the number of concurrent requests to 2. This approach strikes a balance between speed and being considerate to the server we're making requests to.

Rate-Limited As Completed: Using semaphores to limit concurrency.¶

sem = asyncio.Semaphore(2)


async def rate_limited_extract_person(text: str, sem: Semaphore) -> Person:
    async with sem:  # (1)!
        return await extract_person(text)


async def rate_limited_as_completed(sem: Semaphore):
    all_persons = []
    tasks_get_persons = [rate_limited_extract_person(text, sem) for text in dataset]
    for person in asyncio.as_completed(tasks_get_persons):
        all_persons.append(await person)  # (2)!

1. We use a semaphore to limit the number of concurrent requests to 2. This approach strikes a balance between speed and being considerate to the server we're making requests to.

2. We use await here to wait for each task to complete before appending it to the list. This is because as_completed returns a coroutine object, not the result of the coroutine. Alternatively, we can use asyncio.gather to achieve the same result.

Now that we have seen the code, let's examine the results of processing 7 texts. As the prompts become longer or if we use GPT-4, the differences between these methods will become more pronounced.

Results¶

As you can see, the for loop is the slowest, while asyncio.as_completed and asyncio.gather are the fastest without any rate limiting.

Practical implications of async processing¶

The choice of approach depends on the task's nature and the desired balance between speed and resource utilization.

Here are some guidelines to consider:

• Use asyncio.gather for handling multiple independent tasks quickly.
• Apply asyncio.as_completed for large datasets to process tasks as they complete.
• Implement rate-limiting to avoid overwhelming servers or API endpoints.

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