Python 3.14 garbage collection rigamarole

Python 3.14 garbage collection rigamarole(theconsensus.dev)

30 points by eatonphil 1 day ago | 14 comments

vlovich123 2 hours ago |

I suspect 3.14.4 could have been tweaked slightly to address the issue without a revert - they could have prioritized checking the liveliness of objects sorted by size. I’m pretty sure that would fix the max RSS issue without needing a revert and the people unhappy with 3.14 could keep using 3.13 or switch to 3.14 and simply inject explicit calls to gc.gc().

Figuring out how to measure the size of an object can be tricky of course, but I suspect there’s all sorts of things you could try including figuring out how much memory got deallocated after you gc a cycle and attributing it to where the object got allocated as a heuristic to measure the mean allocation size.

nomel 1 hour ago | |

> I suspect 3.14.4 could have been tweaked slightly to address the issue without a revert

I'm sure all the people that have been working on this for years would be interested in your small tweak, that they didn't think of, and would happily accept the PR!

vlovich123 1 hour ago | | |

The options are

a) do work to reduce issues as they come up b) appease the vocal complaints

A takes work, guts, and risk. Option b was chosen with the GC work basically saddled with so much process it’s never going to change. Python has a very storied history of being very committee driven design so the committee did the committee thing.

functionmouse 1 day ago |

> Python 3.14.0 introduced a new incremental garbage collector. But reports of higher memory usage caused the Python team to revert the garbage collector changes in 3.14.5.

If they didn't have very good objective reasons the new GC is better, they never should have shipped it. If they do, they should not have reverted the change.

ameliaquining 2 hours ago | |

It's better in some ways (order-of-magnitude reductions in pause times were cited) but worse in other ways (higher peak memory usage). That the higher peak memory usage was catastrophic for some users only became apparent through post-release feedback.

petre 1 hour ago | | |

They should have shipped it as an addon GC, not enabled by default. One could have turned it on with a command line switch or an env var, just like the Ruby JIT.

hmry 2 hours ago | |

Really? You've never reverted a positive change because it contained a regression only discovered after release?

moron4hire 2 hours ago | |

It's this sort of stuff that leaves me scratching my head why people like Python so much. I hear them say they prefer the syntax and personally I feel like that's such a small part of the holistic experience of working with any particular language. It's one of the reasons why I gave up on C++ years ago for .NET, the whole system of tooling in .NET has never left me feeling like I was pigeonholed into doing things in stupid, self-flagelating ways. Why should I use a language like C++ that doesn't provide a standard set of package management and build tools? Why should I use a language like Python that feels like it's being designed by amateurs?

I felt like the tooling in Racket, CLisp, and Java were similarly pragmatic and not either religiously devoted to some concept of "backwards compatibility" that I seriously doubt most people actually need, or "ease of use" that actually proves itself to be easy when you consider the not-happy-path of the beginner tutorials. Racket, I didn't continue just because the library ecosystem isn't mature enough to keep up with the latest in databases and other 3rd party services. Java I quit largely because of Oracle and some 2010s problems with stagnation. CLisp mostly because it was too hard to socialize. But never because I thought the core language and tooling were holding me back.

hankbond 2 hours ago | | |

It's easy to start learning on, or prototype with, and then sometimes momentum just keeps it going. Also it may not really be the best at anything, but it's "pretty good" at just about everything. It's kind of like vanilla ice cream.

Packaging can be irritating although uv takes the sting out a bit.

You are right that outside of verbosity, once you get used to the syntax of a language, the value of one over the other kind of fades.

SJC_Hacker 2 hours ago | | |

Python is mostly about the “batteries included” standard library and what’s becoming nearly standard third party libs, being able to play around in the REPL,

petre 1 hour ago | | |

> It's this sort of stuff that leaves me scratching my head why people like Python so much

Because of the libraries, not necessarily the language, which is also quite straightforward. For example we found a niche library that speaks the ISO-TP protocol in Python, which allows us to communicate with vehicle ECUs. That's why people also use C++, even tough I quite doubt it's because they like the language. Add to that that it's also heavily used in embedded programming. Yes, you could call a C/C++ library from another language, depending how well the language can do that.

I prefer Ruby, but Python probably has just about everything one would need. It's also great for data processing. We hardly have anything better than pandas, polars, numpy, scipy in other languages and that:s without even mentioning ML tooling.

zzzeek 57 minutes ago |

We definitely noticed behavioral differences in 3.14 regarding gc which could show up in particular test suites we have that are purposely ensuring all objects of a certain type were collected after a gc.collect() run. Between this and other issues (changes to the runtime API for typing, the first decently runnable version of free-threading, kind of a longer time for some C-based dependencies to catch up), the transition for my projects (SQLAlchemy) to 3.14 was generally more bumpy than that of say 3.12 or 3.13. will be interesting to see if 3.14.5 allows us to relax some changes we had to make to the test suite.

irishcoffee 2 hours ago |

The folks running the show as it relates to python remind me a lot about the folks running the show at mozilla.

That is not a compliment.