HackerReposA FIELD GUIDE TO OPEN SOURCE
ProSponsor the shelf♧ 0
← Back to top all-time
plasma-umass
scalene
Python2021–2026
plasma-umass / scalene

scalene

Scalene: a high-performance, high-precision CPU, GPU, and memory profiler for Python with AI-powered optimization proposals

18Distinct people
20Mentions
0Explicit recommenders
13.6KGitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

Scalene: a high-performance, high-precision CPU, GPU, and memory profiler for Python with AI-powered optimization proposals

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

No other repository is repeatedly linked in the same discussions.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 5:04:57 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year20 dated mentions

Observed mentions: 2021-07-05 18:12:51 UTC to 2026-01-10 09:31:25 UTC.

024682021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments20212022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 3 mentions; 0 submissions, 3 comments2023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 8 mentions; 4 submissions, 4 comments20232024-01-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 4 mentions; 1 submissions, 3 comments2025-01-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments2026-01-01 00:00:00 UTC to 2027-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments. Incomplete calendar period.2026*

* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC202
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC303
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC844
20242024-01-01 00:00:00 UTC2025-01-01 00:00:00 UTC413
20252025-01-01 00:00:00 UTC2026-01-01 00:00:00 UTC202
2026 (partial)2026-01-01 00:00:00 UTC2027-01-01 00:00:00 UTC101

What Hacker News says

20 sources
from the youtube description: "Large language models are achieving state-of-the-art results across a wide variety of domains, eclipsing past work in well-studied areas like auto-completion. I argue that they also presage a "Cambrian explosion"—a wave of radically new AI-powered software development tools that will make all our lives easier. I propose a paradigm for how we can best rethink existing tools to leverage a combination of LLMs and PL technologies like static and dynamic analysis. This approach promises to evolve our software tools far beyond their current capacities, including profilers that suggest optimizations, debuggers that identify and propose fixes using real-world knowledge, coverage analyzers that synthesize new tests, compilers that propose fixes for compile-time errors, and data analysis frameworks that analyze your d
Read the rest
ata." Some links from the presentation - https://github.com/plasma-umass#plasma-projects - https://github.com/stephenfreund/flowco Plasma - projects: - RightTyper: Automatically annotates your Python code with high-quality types - https://github.com/righttyper/righttyper - Scalene: A state-of-the-art CPU+GPU+memory profiler for Python, with AI-powered optimization suggestions GitHub stars - https://github.com/plasma-umass/scalene - Coz: A causal profiler that tells you where to optimize your code (C/C++/Rust/Swift/Java) - https://github.com/plasma-umass/coz - CSrankings: Ranks the world's CS departments - https://csrankings.org/ - CoverUp: Automatically generates high-coverage tests - https://github.com/plasma-umass/coverup - Slipcover: Nearly zero-overhead code coverage analysis for Python - https://github.com/plasma-umass/slipcover - ChatDBG: AI-assisted debugging in lldb, gdb, and pdb. Uses AI to answer 'why' - https://github.com/plasma-umass/ChatDBG - CWhy: ("See why") Explains and suggests fixes for C/C++/Rust compiler error messages. - https://github.com/plasma-umass/CWhy - Commentator: Automatically comments Python code, adding docstrings and type annotations - https://github.com/plasma-umass/commentator - SQLwrite: SQLite3 with natural language to SQL, recommends indexes to optimize queries - https://github.com/plasma-umass/sqlwrite
In ATC/OSDI '25 Joint Keynote: Accelerating Software Dev: The LLM (R)Evolution [video]
One major limitation the LLM has is that it can't run a profiler on the code, but we can. (This would be a fun thing to do in the future - feed the output of perf to the LLM and say 'now optimize'). This has been a feature of the Scalene Python profiler (https://github.com/plasma-umass/scalene) for some time (at this point, about 1.5 years) - bring your own API key for OpenAI / Azure / Bedrock, also works with Ollama. Optimizing Python code to use NumPy or other similar native libraries can easily yield multiple order of magnitude improvements in real-world settings. We tried it on several of the success stories of Scalene (before the integration with LLMs); see https://github.com/plasma-umass/scalene/issues/58 - and found that it often automatically yielded the same or better optimizations - see https://github.com/plasma-umass/scal
Read the rest
ene/issues/554. (Full disclosure: I am one of the principal designers of Scalene.)
In LLMs and Code Optimization
I collected a list of profilers (also memory profilers, also specifically for Python) here: https://github.com/albertz/wiki/blob/master/profiling.md Currently I actually need a Python memory profiler, because I want to figure out whether there is some memory leak in my application (PyTorch based training script), and where exactly (in this case, it's not a problem of GPU memory, but CPU memory). I tried Scalene (https://github.com/plasma-umass/scalene), which seems to be powerful, but somehow the output it gives me is not useful at all? It doesn't really give me a flamegraph, or a list of the top lines with memory allocations, but instead it gives me a listing of all source code lines, and prints some (very sparse) information on each line. So I need to search through that listing now by hand to find the spots? Maybe I just don't know how
Read the rest
to use it properly. I tried Memray, but first ran into an issue (https://github.com/bloomberg/memray/issues/212), but after using some workaround, it worked now. I get a flamegraph out, but it doesn't really seem accurate? After a while, there don't seem to be any new memory allocations at all anymore, and I don't quite trust that this is correct. There is also Austin (https://github.com/P403n1x87/austin), which I also wanted to try (have not yet). Somehow this experience so far was very disappointing. Side node, I debugged some very strange memory allocation behavior of Python before, where all local variables were kept around after an exception, even though I made sure there is no reference anymore to the exception object, to the traceback, etc, and I even called frame.clear() for all frames to really clear it. It turns out, frame.f_locals will create another copy of all the local variables, and the exception object and all the locals in the other frame still stay alive until you access frame.f_locals again. At that point, it will sync the f_locals again with the real (fast) locals, and then it can finally free everything. It was quite annoying to find the source of this problem and to find workarounds for it. https://github.com/python/cpython/issues/113939 Another side node: Bloomberg has a couple of nice open source projects. E.g. I just realized, PyStack (https://bloomberg.github.io/pystack/) is also by Bloomberg.
In Memray – A Memory Profiler for Python
From presentation for best paper at OSDI '23 https://www.usenix.org/conference/osdi23/presentation/berger If you think the Simpsons should not be generously featured in an academic presentation, avoid this presentation. Slideshow is very long but worthy of a quick browse because a) good examples on how much 'fatter' python is vs c++ (eg: slide 29) b) shows Scalene improving performance (eg: 90x slide 111) https://github.com/plasma-umass/scalene
In Triangulating Python Performance Issues with Scalene [pdf]

Showing the 15 most recent of 20 sources. Enable JavaScript to search and browse every indexed mention.

MAKE YOURSELF AT HOME

A few shortcuts

/
Search the collection
?
Open this guide
Esc
Close dialogs and navigation

Your saved repositories and interests stay in this browser.