New blog post by @cfbolz.bsky.social: "How fast can the RPython GC allocate?" pypy.org/posts/2025/0...

This year's DLS Most Notable Paper award goes to Compiling for Multi-language Task Migration by Marc Feeley The paper is motivated by the challenges of implementing continuations for an uncooperative environment, and worth a read! Congratulations to the author! www.iro.umontreal.ca/~feeley/pape...

"How slow is the tracing interpreter of PyPy's meta-tracing JIT?" cfbolz.de/posts/speed-... Spoiler: for the microbenchmark I tried, the slowdown of the meta-tracing interpreter is about 900x

We just merged an improvement to the PyPy JIT heap optimizations: type based alias analysis for Python instances. Work was done by @cfbolz.bsky.social and their student Nico Rittinghaus.

nedbatchelder.com/blog/202503/... After nearly two years, I think this is finally ready: coverage․py can use sys.monitoring to more efficiently measure branch coverage.

Fast on the heels of the last release, I have published a PyPy v7.3.19 bug-fix release with PyPy2.7, PyPY3.10 and a beta-quality PyPy3.11. Please try it out! The complete release note is at doc.pypy.org/en/latest/re...

New blog post by my excellent master student Christoph Jung: "Low Overhead Allocation Sampling with VMProf in PyPy's GC" pypy.org/posts/2025/0... Hopefully the first in a series about his work on a sampling allocation profiler for PyPy

Since I was now wondering, here's PyPy VS CPython 3.x binary sizes

We don't do this regularly or anything, but every couple of years @cfbolz.bsky.social looks at how the PyPy binary sizes have developed. Looks like an ok balance between occasionally cleaning something up and thereby shrinking the binary; and then slow growth or explicit time/binary-size-tradeoffs.

As a response to these benchmarks, @cfbolz.bsky.social optimized `itertools.islice` for the common case where no step is given, and also for converting large but not very large integers to strings (basically any int that doesn't fit into 64 bits, but is also not really huge, maybe a few words).

Tim Peters benchmarking Python 3.13 vs PyPy on an OEIS sequence program he wrote: discuss.python.org/t/python-3-1... (the results are complicated, on one version Python 3.13 wins, but on others PyPy does).

Here's the blog post about the PyPY 7.3.18 release that came out yesterday. Thanks to @matti-p.bsky.social, our release manager! This the first version with 3.11 support (beta only so far). Two cool other features in the thread below. pypy.org/posts/2025/0...

PyPy 7.3.18, with Python3.11, 3.10, 2.7 is released. See the release note at doc.pypy.org/en/latest/re...

Hello, World!