Aiohttp performance. AIOHTTP and HTTPX are both useful Python libraries for HTTP requests. 462 WARNING (MainThread) [aiohttp_fast_zlib] zlib_ng and isal are not available, falling back to zlib, performance will be degraded. gather () to run both data-fetching functions concurrently. The page contains all information about aiohttp Server API: Tutorial Quickstart Run a Simple Web Server Command Line Interface (CLI) Handler Resources and Routes Variable Resources Reverse URL Constructing using Named Resources Organizing Handlers in Classes Class Based Views Resource Views Alternative ways for registering routes JSON Response However, if one uses aiohttp, one chooses asynchronous programming, a paradigm that makes the opposite trade-off: more verbosity for better performance. The goal is to improve the time it takes to load data from a remote zarr store (eg on HTTP, GCS, or S3). Streaming Data with aiohttp: My Guide to High-Performance Pipelines When our analytics dashboard started timing out on 50MB+ CSV exports, I knew we had outgrown the traditional request-response model. This approach is often 10x-50x faster for I/O-bound operations. With aiohttp, you can fire all 100 requests simultaneously and handle them as they return. However, if one uses aiohttp, one chooses asynchronous programming, a paradigm that makes the opposite trade-off: more verbosity for better performance. Related On the other hand, aiohttp is an asynchronous HTTP client and server framework which leverages the power of Python’s asyncio library. In the main () function, create a client session to manage HTTP requests. I adapted aiohttp code pretty directly from this post to create a scrip which I am aiming to query my database 40+ times a second so I can benchmark its throttling. connector (aiohttp. Managing request timeouts in aiohttp is crucial for good performance. Default timeouts may cause resource exhaustion and unresponsive UI. For Python developers seeking to leverage async capabilities, aiohttp stands out as a powerful framework that enables both client and server-side HTTP communication using Python's asyncio library. Define two asynchronous functions to fetch data from different API endpoints using aiohttp. Working at a fintech startup processing 2M+ transactions daily, our team of 6 data engineers was struggling with memory-intensive batch processing that was killing our user experience. However, as the individually have their strengths and weaknesses, make sure to understand which situations each of them are better at, and apply them to your applications and API! Aiohttp still takes longer than Go, and becomes substantially unreliable after round 50, dropping anywhere from 30–50% of the messages. Build high-performance Discord bots with aiohttp, the leading asynchronous HTTP client for Python, to prevent blocking and improve concurrency. class aiohttp. StreamResponse(*, status=200, reason=None) [source] ¶ The base class for the HTTP response handling. Contains methods for setting HTTP response headers, cookies, response status code, writing HTTP response BODY and so on. We're making this transition because of a lot of the situations where non-blocking I/O theoretically scales better: Python aiohttp (with asyncio) sends requests very slowly Asked 7 years, 10 months ago Modified 7 years, 10 months ago Viewed 3k times Asynchronous HTTP client/server framework for asyncio and Python - aio-libs/aiohttp. Import asyncio and aiohttp libraries to handle asynchronous operations and HTTP requests. See how HTTPX, Requests, and AIOHTTP libraries compare for sending network requests and find out which one may fit your case better. pradet. cookies (dict) – Cookies to send with the request (optional) headers – HTTP Headers to send with every request (optional). And so the library default behavior reflects this, encouraging you to use performant best practices from the start. To learn more about Requests, read our comprehensive guide to Python Requests Library. Related In high-concurrency networking situations, handling a large number of requests can lead to different behaviors between httpx and aiohttp. This guide covers the essential patterns for Apr 22, 2025 · Leapcell: The Best of Serverless Web Hosting Evaluation of Python HTTP Client Libraries: requests, aiohttp and httpx Among the rich variety of Python HTTP client libraries, the most well-known ones are requests, aiohttp and httpx. See quentin. I’m looking forward to seeing what you build. Performance Comparison Discover the differences between Python's top HTTP clients - Requests, HTTPX, and AIOHTTP. Benchmarking quantifies metrics like requests per second, latency distributions, and resource usage to guide optimization and capacity planning. HTTPX is a newer and more feature-rich HTTP client for Python than the popular Requests library. All the asyncio tests use uvloop for best performance. I arrived at these numbers by testing different configurations to maximize performance. we know per the performance trace that the selectors. This enables the handling of large numbers of simultaneous connections, making it ideal for high-performance applications. Over the past year, my team has been making the transition from Flask to aiohttp. Asynchronous HTTP client/server framework for asyncio and Python - aio-libs/aiohttp Note While aiohttp. For high-performance, non-blocking operations, aiohttp is ideal. In this tutorial, we have only scratched the surface of what you can do with aiohttp and asyncio, but I hope that this has made starting your journey into the world of asynchronous Python a little easier. aiohttp as the developers wanted to make performance a priority. I believe the reason for this dreadful performance is Python itself. Tuning timeouts based on application load and setting them globally can prevent failures and improve user experience. streamer decorator but this approach is deprecated in favor of asynchronous generators as shown above. This post explores how httpx struggles with concurrency and how aiohttp outperforms it in such scenarios Asynchronous clients (like aiohttp or HTTPX) let you fire off hundreds or thousands of requests concurrently without melting your CPU. So this is rather interesting. Use asyncio. If you want flexibility and the ability to choose between synchronous and asynchronous requests, httpx provides a balanced and Hi all, At my current job I'm using aiohttp websockets to subscribe to updates from a 3rd party webserver. Compare FastAPI and AIOHTTP on performance, type checking, request parsing, response formatting, and WebSocket & authentication support. Instead of reporting throughput as requests per second, I use the Flask+Gunicorn test as the baseline, and report the throughput for each test as a multiplier from this baseline. From skimming the linked issue it thankfully seems like there's a lot of inflight work that would bring httpx up to par performance-wise. But if you're trying to measure the performance of the http client, youd want to do a lot of them to average out network jitter, and you want to try to isolate the client itself from overhead like starting the python interpreter or an event loop, and the numbers in the article look exactly what you'd expect if you didn't do those things. On the other hand, aiohttp is an asynchronous HTTP client and server framework which leverages the power of Python’s asyncio library. Dec 26, 2025 · In-depth comparison of HTTPX, Requests, and AIOHTTP, covering features, performance, sync vs async support, pros and cons, and guidance on choosing the right Python HTTP client Requests is a widely-used Python library, especially for making HTTP requests. The current implementation for this is very fast in zarr-python because it uses async, so we have been trying to also start loading chunks from remote storage using async. web. Python’s asyncio provides a framework for writing single-threaded concurrent code using coroutines, event loops, and non-blocking I/O operations. Performance & Community FastAPI is recognized for excellent performance, sometimes comparable to Node. dict, CIMultiDict). Also o Performance Comparison of AIOHTTP and HTTPX To compare the AIOHTTP vs HTTPX performance, we can build a simple program that sends multiple asynchronous GET requests to a website. 0 page for aiohttp 3. test code import uvicorn from fastapi import Fa What’s the difference between AIOHTTP and Flask? Compare AIOHTTP vs. py:select method is causing things to run slowly (doesn't even show up in the fast trace), so it sounds like aiohttp is sub-optimally limiting connections as you suggested. The only way to fairly compare with aiohttp is by bringing the cores of requests, httpx and niquests so that the stack/complexity execution and features served are comparable. Flask in 2026 by cost, reviews, features, integrations, deployment, target market, support options, trial offers, training options, years in business, region, and more using the chart below. js and Go frameworks for API workloads. homeassistant: aiohttp_fast_zlib: zlib_ng not available, performance degraded #330377 Closed as not planned Mindavi opened on Jul 27, 2024 · edited by Mindavi in the given matrix of client, aiohttp is the only one who benefit from built llhttp native C extension to provide a nearly unchallengeable speed. Performance Benchmarks: Our performance tests reveal interesting insights. If you're scraping at scale, making lots of network calls, or trying to reduce latency, the choice of client can make a massive difference in performance and stability, which is why picking the right Python HTTP So @fabiangans and I have been having discussions about improving the performance of Zarr. Here ar How to Make High-Performance HTTP Requests with Aiohttp in Python When using the requests library to fetch 100 URLs, your script waits for each round-trip to complete before starting the next. In today's high-performance web development landscape, asynchronous programming has become essential for building scalable applications. 1: aiohttp still supports aiohttp. This post explores how httpx struggles with concurrency and how aiohttp outperforms it in such scenarios 5. The traffic consists of a lot of small update messages and is very spiky in nature. This article compares the two libraries and discusses their key differences, features, and performance. Its simple API and long existence make it the go-to choice for many developers. , our team supports SockJS, an aiohttp-based library for implementing SockJS-compatible server code. I now think this is definitely a performance issue in aiohttp. Performance Comparison Learn how to install `aiohttp`. In the FastAPI web framework, why is httpx so much worse than aiohttp when facing high concurrent requests? They both reuse the same client instance. CHAPTER Learn how the new asynchronous standard for Python web applications makes apps faster, more flexible, and more future-proof. g. AIOHTTP, first released in October 2014, was one of the first libraries to fully embrace Python’s asyncio framework. Today, AIOHTTP is widely used, with around six million downloads per day as of May 2024. The most important thing you should know about response — it is Finite State Machine. BaseConnector) – BaseConnector sub-class instance to support connection pooling. skip_auto_headers – set of headers for which autogeneration should be skipped. ClientSession. In this tutorial, you’ll learn how Python asyncio works, how to define and run coroutines, and when to use asynchronous programming for better performance in applications that perform I/O-bound tasks. What is aiohttp? WHAT’S NEW IN AIOHTTP 3? Go to What’s new in aiohttp 3. May be either iterable of key-value pairs or Mapping (e. web itself only supports WebSockets without downgrading to LONG-POLLING, etc. While httpx may fail under heavy load, switching to aiohttp offers a more reliable solution for managing high traffic in asynchronous Python applications. Without the help of other third-party libraries, requests can only send synchronous requests; aiohttp can only send asynchronous requests; while httpx has the However, if one uses aiohttp, one chooses asynchronous programming, a paradigm that makes the opposite trade-off: more verbosity for better performance. test code import uvicorn from fastapi import Fa Sep 2, 2019 · In these cases good performance is important, and for now it seems that pure Aiohttp with uvloop can’t be beaten in terms of raw performance if Python is your language of choice, as it is for us. Two popular async HTTP client libraries for Python are aiohttp and httpx. aiohttp is robust and has powered many high-concurrency servers, but requires more manual wiring for features. Deprecated since version 3. me/blog/… for a different implementation than asyncio-throttle specific to aiohttp which correctly limits the number of requests per second instead of just limiting the number of concurrent connections. However we have found Build a high-performance Python function in AWS lambda using asyncio, aiohttp and aiobotocore. 5. - geeogi/async-python-lambda-template The problem 2024-12-13 08:47:37. Learn their features, use cases, and performance benchmarks. 0 major release changes. jl. While AIOHTTP demonstrates a slight edge in handling a large number of asynchronous requests, HTTPX is not far behind Performance Benefits Due to its non-blocking nature, AIOHTTP can offer superior performance, especially in I/O-bound and high-concurrency applications. - oxylabs/httpx-vs-requests-vs-aiohttp The Python aiohttp library provides powerful async HTTP client/server functionality. How to use the ClientSession ? ¶ In these cases good performance is important, and for now it seems that pure Aiohttp with uvloop can’t be beaten in terms of raw performance if Python is your language of choice, as it is for us. Perfect for Python developers looking to enhance their web applications with speed and efficiency. In-depth comparison of HTTPX, Requests, and AIOHTTP, covering features, performance, sync vs async support, pros and cons, and guidance on choosing the right Python HTTP client Interesting, I was not aware there was such a performance discrepancy between aiohttp and httpx. In high-concurrency networking situations, handling a large number of requests can lead to different behaviors between httpx and aiohttp. The choice between aiohttp and httpx depends on specific needs, such as client/server use cases, HTTP/2 support, ease of use, and control over limits and configuration. What version of Home Assistant Core has the issue? core What was the las Asynchronous HTTP client/server framework for asyncio and Python - aio-libs/aiohttp Performance comparison of a wide spectrum of web application frameworks and platforms using community-contributed test implementations. May 22, 2024 · In the FastAPI web framework, why is httpx so much worse than aiohttp when facing high concurrent requests? They both reuse the same client instance. This seems reasonable based on the FastAPI is a modern, fast (high-performance), web framework for building APIs with Python based on standard Python type hints Note While aiohttp. Designed from the ground up for asynchronous operations, it’s an excellent choice for high-performance, concurrent applications. Don't know if it 100% performance related, but on #832 I added a repository with sample code where timeouts happen with httpx, but not with aiohttp with the same request volume. cphhh, x3hpnv, tk7lu, arwx, v4tfm, l1h4up, cbyym, wrrqh, awblgb, t09hvh,