Await for it: mixing async and blocking code - PyCon MEA - Dubai

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⏱ Await for it mixing async and blocking code

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Who am I? Sebastián Ramírez github.com/tiangolo linkedin.com/in/tiangolo twitter.com/tiangolo tiangolo.com Berlin, Germany I created:

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⏱ async / await - concurrency @tiangolo

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⏱ async / await - concurrency @tiangolo

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⏱ async / await - concurrency @tiangolo

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⏱ async / await - concurrency Photo by John Cameron: https://unsplash.com/@john_cameron @tiangolo

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⏱ async / await - concurrency @tiangolo

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⏱ async / await - concurrency @tiangolo

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⏱ async / await - concurrency Photo by Kate Townsend: https://unsplash.com/@k8townsend @tiangolo

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⏱ async / await - concurrency @tiangolo

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@tiangolo 📕 So many terms!

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📕 Concurrency and Parallelism @tiangolo ● Parallel: multiple at the same time ● Concurrent: multiple during the same period of time ○ Normally in turns

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● A lot of waiting? (e.g. multiple users) ○ Concurrency ● A lot of the same CPU work, in multiple cores or GPUs? (e.g. image processing) ○ Parallelism 📕 When concurrency, when parallelism @tiangolo

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● Throughput: amount of items passing through. E.g. requests per second. ○ Concurrency helps. ● Latency: how long each individual item takes. ○ Code optimization ○ Numpy ○ GPUs ○ mypyc ○ Cython ○ Rust 📕 Performance and Speed: throughput or latency @tiangolo

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📕 So many terms! @tiangolo

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@tiangolo 🌪 Using Async

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󰥟 Async rules @tiangolo ● You can only use await inside async functions. ● To call an async function, you need to use await in front of it.

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󰥟 Async rules @tiangolo

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󰥟 Async rules @tiangolo

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🌪 Run an async program with AnyIO @tiangolo

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🌪 Run an async program with AnyIO @tiangolo

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@tiangolo 🌪 Async with FastAPI and HTTPX

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🌪 Async with FastAPI and HTTPX @tiangolo

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🌪 Async with FastAPI and HTTPX @tiangolo

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🌪 Async with FastAPI and HTTPX @tiangolo

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🌪 Async with FastAPI and HTTPX, or not @tiangolo

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🌪 Async with FastAPI and HTTPX optional, or not @tiangolo

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@tiangolo 🌪 Concurrency in your code

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Multiple async function calls - not concurrent ⛔ @tiangolo

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Multiple async function calls - not concurrent ⛔ @tiangolo

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🌪 Multiple async function calls - concurrent @tiangolo

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🔍 Asyncer soonify - inline errors @tiangolo

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🔍 Asyncer soonify - autocompletion @tiangolo

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🔍 Asyncer soonify - concurrent work @tiangolo

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🎁 Return values @tiangolo

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🎁 Asyncer - Soon Values @tiangolo

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🎁 Asyncer - Soon Values - autocompletion @tiangolo

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🎁 Asyncer - Soon Values - inline errors @tiangolo

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🤓 Autocompletion and inline errors everywhere @tiangolo

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😎 Async with Asyncer @tiangolo

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@tiangolo 󰠼 Blocking sync code in async

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󰠼 Blocking sync code in async - don't do this! ⛔ @tiangolo

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󰠼 Blocking sync code in async - don't do this! ⛔ @tiangolo

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󰥟 Blocking sync code in async - performance rules @tiangolo ● Do not call blocking sync code in async code directly. ● Convert it to awaitable. ● Run on another thread.

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󰥟 What is blocking sync code @tiangolo ● Doesn't use async ● Requires waiting for something ● Interacts with something outside your code and variables ○ Network ○ External APIs ○ External databases ○ Files on disk ● Or a lot of CPU for a long time

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🌪 Blocking sync code in async - asyncify @tiangolo

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🔍 asyncify - inline errors @tiangolo

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󰩂 asyncify - autocompletion @tiangolo

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󰩂 Blocking sync code in async @tiangolo

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@tiangolo 🌪 Async in blocking sync in async

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🌪 Async in blocking sync in async - syncify @tiangolo

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󰩂 syncify - autocompletion - inline errors @tiangolo

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🌪 Async in sync in async… @tiangolo

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🌪 Async in blocking sync, dual - syncify @tiangolo

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🌪 Async in blocking sync, dual - syncify @tiangolo ⛔ Warning: performance in mainly sync code won't be the same as async.

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🌪 Async in blocking sync, dual - syncify @tiangolo

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@tiangolo Libraries, what to use ❓

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● Use AnyIO ○ Compatible with both Asyncio and Trio ○ Structured concurrency (task groups) ● Maybe try Asyncer ○ AnyIO + types: autocompletion, inline errors ● Trio ○ Structured concurrency (task groups) ● Asyncio ○ Comes with Python ○ Next versions with task groups ❓ Libraries, what to use @tiangolo

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Thank you! Sebastián Ramírez tiangolo.com fastapi.tiangolo.com github.com/tiangolo linkedin.com/in/tiangolo twitter.com/tiangolo