I'm trying to figure out which approach is better for handling tasks in Python—multithreading or multiprocessing? For larger projects, it seems like both might be necessary, but I lean towards multithreading for smaller ones due to its lower overhead. In a recent project, I had to use multiprocessing because multithreading caused some API calls to freeze while converting playlists to MP3/MP4. I'm curious if there's a more efficient solution out there. Would switching to a different programming language speed things up? Currently, I'm using FastAPI, SocketIO with a Uvicorn backend (Python), and an Apache2 frontend on a Raspberry Pi 5 that I had lying around.
4 Answers
If your conversions rely heavily on tools like ffmpeg, multithreading or async I/O could still work, but you need to ensure you're not blocking the event threads. If the slowdown comes from waiting on external commands, simply switching languages won't speed things up.
You really should profile your application to find the bottlenecks. If you’re hanging somewhere, chances are you aren’t using 'await' properly. Look into where the conversion tasks are being handled and optimize from there!
The conversion's on a Raspberry Pi 5 with three simultaneous tasks using ytdlp. It was too CPU-intensive to handle API calls at the same time, but multiprocessing helped improve that.
Deciding between multithreading and multiprocessing depends on several factors, including your operating system and how resources are managed. Linux, for instance, has lighter processes. It might seem like you need both approaches, but often you can just use one effectively. The ongoing debates in the community about setups like NGINX vs Apache2 show how different processes can manage load in unique ways, especially with event-driven systems. Just keep in mind that the GIL impacts Python’s ability to utilize multithreading for CPU-bound tasks, though there are ongoing improvements in the latest versions.
Python has its quirks, primarily due to the Global Interpreter Lock (GIL), which makes multithreading tricky. In other languages, threads can run in parallel better than in Python. Multiprocessing can be a good alternative, but you’ll need to diagnose what’s slowing down your current setup first. Why are API calls blocked during the MP3 conversion? Are you using a specific library for conversions or calling a shell function? Understanding your current performance bottlenecks is key before making any changes.
You're right about needing to first understand where the delays are. If the MP3 conversion is blocking the main event loop, you might want to review how it's being done. Are you using async functions properly?

Exactly! If the Python function calls are blocking the asyncio loop, switching might not help. They could actually benefit from running in separate threads instead.