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The PyPy Project

@pypyproject.bsky.social
186 followers 16 following 21 posts

The developers of the PyPy project: a fast, compliant, open source Python interpreter. pypy.org github.com/pypy/pypy

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Reposted by The PyPy Project
Tobias @krono.toot.berlin.ap.brid.gy · 25/03/2026
Do I see this right that pypy is immortalized in the python3 Docs? :D
a screenshot from the pyhon3 documentation, argparse. Left: table of contents, right:
```
:et’s show the sort of functionality that we are going to explore in this introductory tutorial by making use of the ls command:

ls
cpython  devguide  prog.py  pypy  rm-unused-function.patch
ls pypy
ctypes_configure  demo  dotviewer  include  lib_pypy  lib-python ...
ls -l
total 20
drwxr-xr-x 19 wena wena 4096 Feb 18 18:51 cpython
drwxr-xr-x  4 wena wena 4096 Feb  8 12:04 devguide
-rwxr-xr-x  1 wena wena  535 Feb 19 00:05 prog.py
drwxr-xr-x 14 wena wena 4096 Feb  7 00:59 pypy
-rw-r--r--  1 wena wena  741 Feb 18 01:01 rm-unused-function.patch
ls --help
Usage: ls [OPTION]... [FILE]...
List information about the FILEs (the current directory by default).
Sort entries alphabetically if none of -cftuvSUX nor --sort is specified.
...

```
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Reposted by The PyPy Project
Laurence Tratt @ltratt.bsky.social · 15/04/2026
C interpreters underlie many of our most widely used language implementations -- but they're slow. Wouldn't it be great if we could turn them into JIT compiling VMs? This video shows what happens when we do just that to the normal Lua VM (first) and "yklua" (Lua w/JIT, second).
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Reposted by The PyPy Project
oberstet.bsky.social @oberstet.bsky.social · 07/11/2025
#Autobahn v25.10.2 Released: #WebSocket & #WAMP for Python with Critical Fixes and Enhanced CI/CD, #PyPy Support, Binary Wheels, and native NVX (SIMD vector acceleration) - **📋 Full Announcement:** github.com/crossbario/a... - **🌐 WAMP Protocol:** wamp-proto.org
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The PyPy Project @pypyproject.bsky.social · 15/06/2025
New blog post by @cfbolz.bsky.social: "How fast can the RPython GC allocate?" pypy.org/posts/2025/0...
pypy.org
How fast can the RPython GC allocate?
While working on a paper about allocation profiling in VMProf I got curious about how quickly the RPython GC can allocate an object. I wrote a small RPython benchmark program to get an idea of the ord
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Reposted by The PyPy Project
Stefan Marr @stefan-marr.de · 09/06/2025
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...
The award with the following citation:

Recent years have seen a resurgent interest in the use and implementation of first-class control, especially in the form of delimited continuations via effect handlers. This paper is motivated by the challenges of implementing continuations for an uncooperative environment and the opportunities for code migration that the implementation affords. The paper recaps the design of the Gambit Virtual Machine for efficient continuations, and it provides evidence for the ongoing effectiveness of the design.
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Reposted by The PyPy Project
CF Bolz-Tereick @cfbolz.bsky.social · 12/06/2025
"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
cfbolz.de
How slow is the tracing interpreter of PyPy's meta-tracing JIT?
I wanted to investigate the warmup behavior of the PyPy interpreter, so I wrote a somewhat arbitrary microbenchmark: all_results = set() num = int(sys.argv[1]) class A(object): pass def main():
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The PyPy Project @pypyproject.bsky.social · 21/05/2025
Adding heap operations to Z3 didn't actually find any bugs in the JIT optimizer for heap operations. Maybe that's not entirely surprising, because miscompilations in that area tend to lead to crashes pretty quickly. In any case, it's good to have that infrastructure for the future.
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The PyPy Project @pypyproject.bsky.social · 21/05/2025
We also added limited support for generating random heap operations to our JIT optimizer fuzzer. This extends previous work, which supported only int operations in Z3: pypy.org/posts/2022/1...
pypy.org
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The PyPy Project @pypyproject.bsky.social · 21/05/2025
Christoph Jung, another student @cfbolz.bsky.social, added a memory model to our Z3 based translation validation. Now our CI checks whether our optimizer unit tests contain invalid optimizations using Z3.
pypy.org
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The PyPy Project @pypyproject.bsky.social · 21/05/2025
Micro-benchmarks for both optimizations look great, but both are hard to see in the performance of bigger programs.
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The PyPy Project @pypyproject.bsky.social · 21/05/2025
An unrelated optimization we also merged was to make store-to-load and load-to-load forwarding work for array reads and writes where the index is a variable. This already worked for constant indexes before.
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The PyPy Project @pypyproject.bsky.social · 21/05/2025
We've already had type based alias analysis before, but only taking the RPython level types into account. Unfortunately instances of different Python classes get represented as instances of the same RPython type, making the old JIT logic useless for distinguishing them, which is now fixed.
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The PyPy Project @pypyproject.bsky.social · 21/05/2025
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.
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Reposted by The PyPy Project
Ned Batchelder @nedbat.com · 09/03/2025
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.
nedbatchelder.com
Faster branch coverage measurement
After nearly two years, I think this is finally ready: coverage.py can use <a rel="external noopener" href="https://docs.python.org/3/library/sys.monitoring.html">sys.monitoring</a> to more efficientl...
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Reposted by The PyPy Project
matti-p.bsky.social @matti-p.bsky.social · 26/02/2025
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...
doc.pypy.org
PyPy v7.3.19: release of python 2.7, 3.10 and 3.11 beta, released 2025-02-26 — PyPy documentation
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Reposted by The PyPy Project
CF Bolz-Tereick @cfbolz.bsky.social · 25/02/2025
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
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Reposted by The PyPy Project
CF Bolz-Tereick @cfbolz.bsky.social · 13/02/2025
Since I was now wondering, here's PyPy VS CPython 3.x binary sizes
Plot of CPython and PyPy binary sizes over time. CPython 3.7 is 35 MiB, shrinks to 22.5 MiB in 3.8, then slowly grows again until 3.11 at 25.2 MiB. Cpython 3.12 is much bigger, at 37.3 MiB.  CPy 3.13 shrinks a bit again to 36.1 MiB.

PyPy tracks the ups and downs in roughly the same shape but is generally much bigger. 3.7 is at 60.5, 3.8 at 56.2, then it slowly increases to 58.8 at PyPy 3.11
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The PyPy Project @pypyproject.bsky.social · 13/02/2025
Interestingly enough PyPy 3.x is mostly smaller than 2.7. E.g. PyPy 3.11 is 58.8 MiB, despite having a bunch more features. I never quite figure out why. Just for comparison, CPython 3.11 is 25.2 MiB.
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The PyPy Project @pypyproject.bsky.social · 13/02/2025
This is the size of PyPy 2.7, btw. It doesn't make sense to use the 3.x variant for this, because the size of that changes due to newer Python versions being implemented over time.
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The PyPy Project @pypyproject.bsky.social · 13/02/2025
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.
plot showing how the PyPy binary went from 68 MiB in early 2020 to 61 MiB today, with a few ups and downs in between. various points in time are annotated with reasons for growth and shrinkage. the biggest shrinkage is: 2022-05-10 compact jitcode liveness info
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The PyPy Project @pypyproject.bsky.social · 09/02/2025
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).
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The PyPy Project @pypyproject.bsky.social · 09/02/2025
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).
discuss.python.org
Python 3.13.0 speed
This is a hearty “congratulations!” message. I often tackle a problem inspired by The On-Line Encyclopedia of Integer Sequences (OEIS). Here, sequence A378048: integers k such that k and k**2 together...
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The PyPy Project @pypyproject.bsky.social · 07/02/2025
So far this is a rather low-level mechanism, there's no convenient pdb integration yet. We plan to add something like that later, for now you can use a third-party package such as sdb to get an actual remote debugger going: github.com/ryanpetrello...
github.com
GitHub - ryanpetrello/sdb: a socket-based remote debugger for Python
a socket-based remote debugger for Python. Contribute to ryanpetrello/sdb development by creating an account on GitHub.
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The PyPy Project @pypyproject.bsky.social · 07/02/2025
The other new feature an implementation of the draft PEP 768, "Safe external debugger interface" (again, Linux only so far). PEP was written by @pablogsal.com et al. It allows you to remotely attach to a running PyPy process and inject Python code into it. doc.pypy.org/en/latest/re...
doc.pypy.org
Remote Debugging — PyPy documentation
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The PyPy Project @pypyproject.bsky.social · 07/02/2025
We have further features planned for VMProf, including a stochastic memory profiler hopefully coming out later this year.
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The PyPy Project @pypyproject.bsky.social · 07/02/2025
Here's a screenshot of the Firefox Profiler UI showing VMProf output. The blue functions are native functions, yellow is Python functions and orange jitted functions (no example of that is in the screenshot).
A screenshot of the Firefox profiler UI. It shows a hierarchically expandable view of stack traces together with counts of which stack traces were seen how often during sampling. The top layers of a stack trace are always yellow Python functions. the bottom layers show the native functions that these Python functions call in blue. One of the functions is selected, with extra information shown in a pane on the right.
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The PyPy Project @pypyproject.bsky.social · 07/02/2025
It works best by combining it with vmprof-firefox-profile, which converts vmprof output to a format the Firefox Profiler UI can read: github.com/Cskorpion/vm... (We're still working on a PyPI release of this tool.)
github.com
GitHub - Cskorpion/vmprof-firefox-converter: Firefox-Profiler as UI for VMProf
Firefox-Profiler as UI for VMProf. Contribute to Cskorpion/vmprof-firefox-converter development by creating an account on GitHub.
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The PyPy Project @pypyproject.bsky.social · 07/02/2025
VMProf on PyPy can now sample native functions and symbolify their names (Linux only at the moment). VMProf for CPython has had that feature for a while, we've now ported it to PyPy.
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The PyPy Project @pypyproject.bsky.social · 07/02/2025
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.org
PyPy v7.3.18 release
PyPy v7.3.18: release of python 2.7, 3.10 and 3.11 beta The PyPy team is proud to release version 7.3.18 of PyPy. This release includes a python 3.11 interpreter. We are labelling it "beta" because it
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Reposted by The PyPy Project
matti-p.bsky.social @matti-p.bsky.social · 06/02/2025
PyPy 7.3.18, with Python3.11, 3.10, 2.7 is released. See the release note at doc.pypy.org/en/latest/re...
doc.pypy.org
PyPy v7.3.18: release of python 2.7, 3.10 and 3.11 beta, released 2025-02-06 — PyPy documentation
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The PyPy Project @pypyproject.bsky.social · 06/02/2025
Hello, World!
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