alt.hn

6/12/2026 at 11:59:40 AM

Python 3.14 garbage collection rigamarole

 https://theconsensus.dev/p/2026/06/06/python-3-14-garbage-collection-rigamarole.html

by eatonphil

6/14/2026 at 8:55:03 AM

Do people use python for new projects apart from ML stuff which hasn't moved to all-native yet?

My experience with Python is a really bad one for professional work: it's chaotic and slow, and has by far the worst versioning and packaging story of any mainstream language, yet its proponents keep praising it in denial.

I guess Python is an ok target for agentic coding, but my god do look Claude's commit messages pretentious, with code bases quickly heading into absolute unmaintainability. At least it had found gross JS injection vectors in a Django app that really shouldn't have made it through a code review, architecture level as they were, but oh well. A mature Django app is also not a nice dev experience IMO, with tons of implicit behavior all over the place encoded in a mix of magic filenames, database naming conventions, and URL routing quickly descending into regexp hacks.

by tannhaeuser

6/14/2026 at 8:58:54 AM

Half or more of the scientific research community live and breathe Python. Granted, it's Python 3.12, as 3.13 broke most of the C API, and everything COBOL and Fortran just about ground to a halt. But new projects are spun up constantly.

by shakna

6/14/2026 at 8:29:50 AM

The usual GC tradeoff is between memory and CPU performance. If you set the memory max high, the GC will run less often, you get less pause time.

So I do not understand why it's a surprise that minimizing the pause time requires more memory. Is it because there is no knob to set either the max pause time or the max memory ?

by _old_dude_

6/14/2026 at 8:55:11 AM

Instead of "Reference counting primer" I would like to see a primer on how exactly such a huge change can go into Python without formal PIP process.

by watt

6/14/2026 at 3:38:59 AM

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.

by vlovich123

6/14/2026 at 4:15:08 AM

> 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!

by nomel

6/14/2026 at 4:24:52 AM

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.

by vlovich123

6/14/2026 at 6:04:03 AM

Anyone who’s worked in incident response will tell you why you’re wrong.

Tweaking the GC while the system was functionally broken is the worst time to do it. Correct incident response is revert first, figure out how to fix it later.

by scott_w

6/14/2026 at 4:30:19 AM

I do find the BDFL approach much better for language design. You might disagree with the direction of the language, but there is usually a "philosophy" or "taste" driven by one person that tends to be consistent over time.

In fact, I think Guido himself resigned due to the experience he had trying to get a PEP through the committee.

by evilturnip

6/14/2026 at 9:00:14 AM

but I aways use Python to analysis my medical data.

by zhanbing

6/14/2026 at 4:48:15 AM

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.

by zzzeek

6/14/2026 at 7:06:46 AM

There was an issue recently with synapse, tbe matrix server implementation, where ram usage would grow until OOM.

The solution was to upgrade Python. But I won't, because that was the problem in the first place, here, apparently.

Oddly if I ran the whole thing under memray with a different allocator, no issue. I say oddly but it isn't.

So I guess my matrix server is broken until I rehome it on a new server with a fresh python instead of 3.10.8.

by picofarad

6/14/2026 at 8:58:31 AM

Just run it under uv :)

by a_t48

6/14/2026 at 3:05:57 AM

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.

by irishcoffee

6/14/2026 at 9:14:21 AM

[flagged]

by sspoisk

6/12/2026 at 12:04:19 PM

> 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.

by functionmouse

6/14/2026 at 3:16:59 AM

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.

by ameliaquining

6/14/2026 at 4:08:54 AM

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.

by petre

6/14/2026 at 3:39:42 AM

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

by hmry

6/14/2026 at 3:04:47 AM

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.

by moron4hire

6/14/2026 at 8:52:26 AM

You are right the syntax is a small part of it, but it is more important than you say in this case because Python syntax is one of the things that makes it very readable.

Even if you dislike the direction Python is going in, a lot of what attracted people to Python in the first place is still there. The readability, the large standard library, the huge ecosystem. There are libraries and frameworks for everything: numerical stuff, web development, GUIs etc. Its actually a nice language in itself, just going in the wrong direction now.

If you look at it historically it was really good comparatively. If you compare it to the alternatives available 20 years ago it looks pretty good.

by graemep

6/14/2026 at 7:52:34 AM

> Racket, CLisp

Syntax really does matter more than you give it credit for. Were that not the case, I'd expect one Lisp or Scheme dialect or other to take Python's place. Outside of that counterfactual, Python's competition was stuff like Ruby, and it turned out that network effects were also pretty important.

by zahlman

6/14/2026 at 3:40:59 AM

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.

by hankbond

6/14/2026 at 6:38:06 AM

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

uv proves the OP’s point. Why couldn’t the core team and the core-adjacent PyPA make a tool as liked as uv, and why is the Python package manager uv written in Rust and not Python?

by Kwpolska

6/14/2026 at 6:47:36 AM

For the same reason GP posted and half the stdlib is written in C: Python is a language that is almost always good enough, but never really the best (and especially when it comes to performance of complex algorithms).

by necovek

6/14/2026 at 6:50:38 AM

Because uv itself can fetch a Python distribution. If it's written in Python, it's quite a bit harder to distribute, assuming one of their goals is not to require an existing Python install.

by CamouflagedKiwi

6/14/2026 at 7:40:57 AM

> Why couldn’t the core team and the core-adjacent PyPA make a tool as liked as uv

Incredibly large backward-compatibility burdens [0], internal politics [1] and general institutional dysfunction (no footnote; if you're familiar then you need no explanation, and if you aren't then the less said the better). Nothing to do with Python as a language. Most of the important pieces to get uv-like performance are algorithmic choices, and most of the rest are available as built-in C code in the reference implementation [2].

(Edit: wait, I recognize your username. You should definitely know these sorts of things.)

> why is the Python package manager uv written in Rust and not Python?

Because that's the language that Astral devs like, and because installing Python itself is considered in scope for uv so there would be an intractable bootstrapping issue.

[0]: In particular, the entire model of `setup.py` defining metadata is certifiably insane, especially when you consider the projects that expect to feed that code to Setuptools at build time in order to figure out what version of Setuptools is needed at build time. But this legacy approach is seen as something that absolutely must be guaranteed to work for well beyond even now; even attempts to remove long-deprecated, minor aspects of that functionality end up breaking major projects, including ones that didn't even require a build step in the first place [3].

[1]: Most obviously, GvR not wanting to have anything to do with it when initially approached by the SciPy people in IIRC 2011, leading to the creation of Conda). But a lot of other things, too. The backwards-compatibility issues synergize with this; consider for example the architectural dumpster fire of Setuptools, and the timeline of distutils removal from the standard library.

[2]: See e.g. my analysis in https://zahlman.github.io/posts/oxidation/ .

[3]: See e.g. my LWN article https://lwn.net/Articles/1020576/ .

by zahlman

6/14/2026 at 6:50:18 AM

C++ has vcpkg, conan, cmake and ninja nowadays.

They are as standard as arguing about Ant, Maven, Gradle in Java, npm, pnpm, yarn in node, and so on.

However I fully agree with the gist of your comment, basically Python is the new BASIC.

However at least BASIC was compiled, with exception of the 8 bit home micros.

by pjmlp

6/14/2026 at 3:22:56 AM

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,

by SJC_Hacker

6/14/2026 at 7:50:04 AM

> “batteries included” standard library and what’s becoming nearly standard third party libs

Historically, the standard library made sense. And we're talking about a history that stretches back to before Internet connections were ubiquitous, to say nothing of connection speed.

Now the standard library is full of things that they refuse to remove because it would supposedly be too disruptive, but which they would never think of adding today if they weren't already there.

by zahlman

6/14/2026 at 6:18:04 AM

The standard library is full of dead batteries. If the stdlib is so good, why does everyone install requests instead of using the stdlib http client? And why requests or something like it hasn't been adopted into stdlib after so many years of stability?

by Kwpolska

6/14/2026 at 9:08:44 AM

You are picking one of the weak points of the standard library and an unusually popular replacement (and AFAIK it is built on the standard library). I cannot think of many others that are widely used. Maybe lxml ?

A Python codebase might well use requests, but it will almost always also heavily use the standard library.

by graemep

6/14/2026 at 6:51:19 AM

Parts of requests has been adopted into stdlib: https://docs.python.org/3/library/urllib.request.html

People mostly defer to requests because they do not track language development closely and because we are creatures of habit.

I try to avoid non-stdlib packages when stdlib will do a good job, but I received negative feedback from people who aren't aware of the updates and couldn't foresee supply-chain attacks.

by necovek

6/14/2026 at 7:48:03 AM

The current standard library urllib is a refactoring of previous attempts from the 2.x standard library, and urllib.request is just a sub-package. It does not represent adoption of requests; requests builds on urllib3, which was created to fill in gaps in what the standard library provided, and named like that because the 2.x standard library had both a `urllib` and a `urllib2` as they struggled to figure it out.

by zahlman

6/14/2026 at 9:06:33 AM

Because the typical Python programmer does not appreciate the advantages of a slightly rusty stdlib compared to reaching for the bedlam that is PyPI.

by BoingBoomTschak

6/14/2026 at 3:46:10 AM

> 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.

by petre