[scarygliders]

> For the second type of system, I can't remember the last time where I wrote one where I had in-process parallelism/concurrency with shared resources (even in langs where there's no GIL). It would just get too confusing and hard to reason about. Any optimizations were mostly based on intelligent batching. For parallelism, you'd just have multiple _completely_ independent processes, probably across multiple machines.

For myself, the prospect of no-gil is interesting, in that something like my Captain's Log application [0] can be free from it; for example, I currently use a QThread to implement a JournalParser, which is basically the program's "engine" - the parser constantly reads in game events from a player journal file generated by the game Elite: Dangerous (and Odyssey), and depending on the particular event, fires off a related custom QSignal, which is then processed by whichever slot (receiving function) is listening for a given Signal.

There are other places in that application where no GIL might be quite handy.

In other words, I can see where having no GIL can be useful for GUI applications like mine.

[0] https://captainslog.scarygliders.net/captains-log-2/

[radarsat1]

Your JournalParser sounds like it could be implemented using normal Python threads or by an asyncio event loop without much performance problems. If I understand all it's doing is watching for events and posting a signal somewhere, so it doesn't sound like the kind of application that is CPU-bound.

[scarygliders]

I could. But I 100% take full advantage of Qt's signal and slot mechanism.

Also, in many ways, GUI applications written in Python are not so much CPU bound, but Python GIL bound. If you're writing a Python/Qt application, you have to take great care to ensure your GUI doesn't freeze when your program is performing, say, many database inserts; if you have some naive loop which performs some given operation, your nice Qt GUI will freeze right up until that operation is complete. Right now the solution is to perform such operations in, say, a QThread, and use Qt's signal/slot feature to blat a progress "report" to a handler in the `main` Python loop.

So back to what I said - no-GIL is looking quite interesting to me. Whether or not Qt can take advantage of such will be a different matter.

[nullspace]

I agree. UIs written in python could benefit massively from noGIL - complex / computational UIs especially.