Lossless data compression is an important tool for reducing the storage requirements of the world's ever-growing data sets. Yann Collet developed the LZ4 algorithm and designed the Zstandard (or Zstd) algorithm; he came to the 2025 Open Source Summit Japan in Tokyo to talk about where data compression goes from here. It turns out that we have reached a point where general-purpose algorithms are only going to provide limited improvement; for significant increases in compression, while keeping computation costs within reason for data-center use, turning to format-specific techniques will be needed.

On her blog, Julia Evans writes about improving Git documentation, including a new data model man page she wrote with Marie LeBlanc Flanagan, and updates to the pages for several other Git sub-commands (add, checkout, push, and pull). As part of the process, she asked Git users to describe problems they had run into in the documentation, which helped guide the changes that she made.

I'm excited about this because understanding how Git organizes its commit and branch data has really helped me reason about how Git works over the years, and I think it's important to have a short (1600 words!) version of the data model that's accurate.

The "accurate" part turned out to not be that easy: I knew the basics of how Git's data model worked, but during the review process I learned some new details and had to make quite a few changes (for example how merge conflicts are stored in the staging area).

At the 2025 Linux Plumbers Conference (LPC), held in Tokyo in mid-December, Changwoo Min led a session on what he has learned while developing the "latency-criticality aware virtual deadline" (LAVD) scheduler, which is aimed at gaming workloads. The session was part of the Gaming on Linux microconference, which is a new entrant into LPC; organizers hope to see it return next year in Prague and, presumably, beyond. LAVD uses the extensible scheduler class (sched_ext) and has the primary goal of minimizing stuttering in games; it is implemented in a combination of BPF and Rust.

At Open Source Summit Japan 2025, Erin McKean talked about the challenges to producing good project documentation, along with some tooling that can help guide the process toward success. It is a problem that many projects struggle with and one that her employer, Google, gained a lot of experience with from its now-concluded Season of Docs initiative. Through that program, more than 200 case studies of documentation projects were gathered that were mined for common problems and solutions, which led to the tools and techniques that McKean described.

Dictionaries are ubiquitous in Python code; they are the data structure of choice for a wide variety of tasks. But dictionaries are mutable, which makes them problematic for sharing data in concurrent code. Python has added various concurrency features to the language over the last decade or so—async, free threading without the global interpreter lock (GIL), and independent subinterpreters—but users must work out their own solution for an immutable dictionary that can be safely shared by concurrent code. There are existing modules that could be used, but a recent proposal, PEP 814 ("Add frozendict built-in type"), looks to bring the feature to the language itself.

The Django Python web framework project has announced the release of Django 6.0 including many new features, as can be seen in the release notes. Some highlights include template partials for modularizing templates, a flexible task framework for running background tasks, a modernized email API, and a Content Security Policy (CSP) feature that provides the ability to "easily configure and enforce browser-level security policies to protect against content injection".

Security updates have been issued by Debian (krita and tryton-server), Oracle (bind9.18, ipa, kernel, libssh, redis, redis:7, sqlite, sssd, and vim), Slackware (cups), SUSE (containerd, cups, curl, dovecot24, git-bug, gitea-tea, glib2, grub2, himmelblau, java-25-openjdk, kernel, libmicrohttpd, libvirt, pnpm, powerpc-utils, python311, python313, redis, rnp, runc, sssd, tomcat11, unbound, and xwayland), and Ubuntu (cups, libxml2, openvpn, and webkit2gtk).

Security updates have been issued by Debian (kdeconnect, libssh, and samba), Fedora (7zip, docker-buildkit, and docker-buildx), Oracle (bind, buildah, cups, delve and golang, expat, firefox, gimp, go-rpm-macros, haproxy, kernel, lasso, libsoup, libtiff, mingw-expat, openssl, podman, python-kdcproxy, qt5-qt3d, runc, squid, thunderbird, tigervnc, valkey, webkit2gtk3, xorg-x11-server, and xorg-x11-server-Xwayland), SUSE (buildah, cloudflared, containerd, expat, firefox, gnutls, helm, kernel, libxslt, mysql-connector-java, ongres-scram, openbao, openexr, openssh, podman, python311, python312, ruby2.5, rubygem-rack, runc, samba, sssd, tiff, unbound, and yelp), and Ubuntu (edk2, ffmpeg, h2o, python3.13, rust-openssl, and valkey).

The Racket programming language project has released Racket version 9.0. Racket is a descendant of Scheme, so it is part of the Lisp family of languages. The headline feature in the release is parallel threads, which adds to the concurrency tools in the language: "While Racket has had green threads for some time, and supports parallelism via futures and places, we feel parallel threads is a major addition." Other new features include the black-box wrapper to prevent the compiler from optimizing calculations away, the decompile-linklet function to map linklets back to an s-expression, the addition of Weibull distributions to the math library, and more.

Unpacking Python iterables of various sorts, such as dictionaries or lists, is useful in a number of contexts, including for function arguments, but there has long been a call for extending that capability to comprehensions. PEP 798 ("Unpacking in Comprehensions") was first proposed in June 2025 to fill that gap. In early November, the steering council accepted the PEP, which means that the feature will be coming to Python 3.15 in October 2026. It may be something of a niche feature, but it is an inconsistency that has been apparent for a while—to the point that some Python programmers assume that it is already present in the language.