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Konstantinos Kallas

@konstantinoskallas

Assistant Professor of CS at UCLA // Systems, Compilers, PL // he/they Website: https://angelhof.github.io/

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20.11.2024
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Latest posts by Konstantinos Kallas @konstantinoskallas

Very cool work!

25.02.2026 14:59 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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pash Light-touch Data-Parallel Shell Processing

PaSh finally got a PyPI package (pypi.org/project/pash/) ๐ŸŽ‰

Install with `pip install pash` and start parallelizing your ๐Ÿซต shell scripts today!

30.01.2026 11:49 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

If you (or anyone you know) would like to do your PhD in a vibrant city with great weather, next to the sea, and the mountains, make sure to apply to UCLA and mark my name as a potential advisor :)

20.11.2025 22:53 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
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I am hiring 1-2 PhD students this cycle at UCLA. My group works on problems in the intersection of systems and PL, with some recent topics of interest being the correctness of black-box side-effectful programs, Python script optimization, and systems for cloud computing!

20.11.2025 22:53 ๐Ÿ‘ 4 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

Stephen (@stephenmell.bsky.social) is also looking for postdoc opportunities so reach out to him if you are working in the intersection of PL, ML, and systems and are looking to hire! He is amazing!

30.10.2025 19:58 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

You can find a lot more information on our work, proofs, details, additional evaluation, and more ๐Ÿ˜ฎ in our paper that Stephen (@stephenmell.bsky.social) presented at OOPSLA a few weeks ago. You can also read it here: dl.acm.org/doi/pdf/10.1...

30.10.2025 19:58 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

We prove correctness by proving that the semantics is confluent ๐Ÿšฐ , meaning that even if different execution steps are happening with our opportunistic evaluation, they will all lead to the same final program state.

30.10.2025 19:58 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

But why is that correct you may think to yourself? ๐Ÿค” Thanks for asking, I wouldnโ€™t have thought to tell you!

We have proved that our approach is โœจ correct โœจ, meaning that the behavior of the program does not change when executed with opportunistic evaluation.

30.10.2025 19:58 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

We then use everyoneโ€™s favorite technique (Church โ›ช encodings) to desugar control flow of a high level language down to our calculus enabling streaming and parallelization for programs that involve LLMs and other ML models.

30.10.2025 19:58 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

Our key insight is an evaluation strategy that is neither totally strict, nor totally lazy, and can automatically exploit parallelization and streaming. We build this evaluation strategy on top of a core calculus with first class support for external calls (like ones to an LLM).

30.10.2025 19:58 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

To address this, we built a novel ๐Ÿ‡opportunistic ๐Ÿ‡ evaluation system that automatically parallelizes independent calls and streams their results! Our system reduces the execution time of this script from 51s to 9s, and the first output arrives on the terminal after only 1.3s!

30.10.2025 19:58 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

In the example script in the image above, all calls to the LLM are completely ๐Ÿœ๐Ÿœ๐Ÿœ sequentialized ๐Ÿœ๐Ÿœ๐Ÿœ and there is no streaming. This script takes about 51 seconds to execute, and it took more than 7 seconds to start seeing output written in the terminal.

30.10.2025 19:58 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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Are you making calls to LLMs and ML models in your code? Is your code awfully sequentialโ„ข? Is your code unable to stream data?

Look no further! Stephen (@stephenmell.bsky.social), Osbert, Steve, and I came up with a solution for you! Read further if you suffer from the above issues โฌ‡๏ธ

30.10.2025 19:58 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
FLoC 2026: The 9th Federated Logic Conference

The worldโ€™s largest federated conference in logic & automated reasoning, FLoC 2026 (www.floc26.org), will be in Lisbon!
Thousands will attendโ€”an excellent chance for companies to showcase their presence. Interested in sponsoring? Details www.floc26.org/sponsors/FLo...

15.09.2025 23:08 ๐Ÿ‘ 6 ๐Ÿ” 5 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

There is some alignment between these two threads indeed I think! Happy to chat whenever :)

02.07.2025 06:31 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

In this paper we don't yet build such guardrails but primarily talk about what these guardrails should/could look like! We also focus on guardrails at the systems and PL level, instead of improving the agents. The paper is short so please read it and share your thoughts with us :)

01.07.2025 13:43 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

People use LLM agents to interact with (access/modify) their system and external services. We (@bimalraj.bsky.social, @samkumar.bsky.social, and Sai) think this can be a bit dangerous ๐Ÿ’ฃโฒ๏ธ๐Ÿ’ฅ so we wrote a paper (arxiv.org/pdf/2506.13028) on system guardrails for such agent-driven interactions!

01.07.2025 13:43 ๐Ÿ‘ 4 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
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Static analysis proposed to โ€˜rehabilitateโ€™ shell programs Semantics-driven static analysis could be used to improve the safety, correctness, and performance of Unix, Linux, and macOS shell scripts, researchers say.

An article written just came out covering our latest work on semantic-driven static analysis for shell script correctness (www.infoworld.com/article/3977...). There will also be a presentation at HotOS on Thursday (sigops.org/s/conference...) for anyone who is there!

13.05.2025 00:03 ๐Ÿ‘ 3 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

๐Ÿ˜ ๐Ÿ˜ ๐Ÿ˜ ๐Ÿ˜ 

01.04.2025 21:05 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
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PLMW @ PLDI 2025 - Programming Languages Mentoring Workshop - PLDI 2025 The Programming Language Mentoring Workshop (PLMW) aims to broaden the exposure of late-stage undergraduate students and early-stage graduate students to research and career opportunities in programmi...

PLMW@PLDI'25 is now accepting applications: pldi25.sigplan.org/home/PLMW-pl...

Deadline: April 10, 2025

PLMW an excellent place to learn about exciting PL research, from the ground up, and to find your PL friends!

Please apply!

28.03.2025 03:56 ๐Ÿ‘ 17 ๐Ÿ” 9 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 1

I am looking to recruit a PhD student (fully funded at UK home tuition rate) to work on automated testing and verification of machine learning compilers and runtimes! Deadline: 30th April. Please spread the word! Details here: www.doc.ic.ac.uk/~afd/PhD-Adv...

18.03.2025 18:50 ๐Ÿ‘ 7 ๐Ÿ” 6 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

The data includes statistical information about the shapes and sizes of real-world Durable Functions applications. We hope that it will provide new insights to the community and indicate directions for future work!

23.02.2025 22:15 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
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Netherite: efficient execution of serverless workflows - The VLDB Journal Serverless applications are popular because they can provide scalability and load-based billing with minimal developer effort. Beyond simple stateless functions (FaaS), modern serverless programming m...

An extended version of our Netherite paper with folks from Microsoft Research was just published to the VLDB Journal (link.springer.com/article/10.1...). The key addition is Section 8, which contains real usage data for Durable Functions. See more below โฌ‡๏ธ

23.02.2025 22:15 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Text from student paper review writing: "Could have named it MuStash instead of MuCache"

Text from student paper review writing: "Could have named it MuStash instead of MuCache"

A student in my paper reading class at UCLA identified a serious missed opportunity in our MuCache paper:

30.01.2025 21:49 ๐Ÿ‘ 10 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

Hey all! Who's at POPL? If you're here and looking to do a PhD at Princeton, let's chat!

20.01.2025 20:22 ๐Ÿ‘ 32 ๐Ÿ” 13 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

Consider following the โœจnewโœจ and official PLDI account on Bluesky @sigplan-pldi.bsky.social

20.01.2025 21:42 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
Home ยท SoCal PLS

SoCal Programming Languages and Systems is back and will be @ucsd_cse in February!
Submit your abstracts!
socalpls.github.io

@ranjitjhala.bsky.social @manu.sridharan.net @cristalopes.bsky.social
Reposts appreciated!

20.12.2024 19:50 ๐Ÿ‘ 24 ๐Ÿ” 11 ๐Ÿ’ฌ 2 ๐Ÿ“Œ 1

This is joint work with @akisg.bsky.social , Paul Loh, Shuyue Wang, Justin Qiu, Max Demoulin, and Benjamin Lee.

Stay tuned for a preprint ๐Ÿ“š

Finally, Akis ( @akisg.bsky.social ) is applying for PhDs this cycle so snatch him while you have a chance!!

12.12.2024 03:11 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
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Rajลmon - Wikipedia

The name means city gate, representing the controller rejecting requests (en.wikipedia.org/wiki/Raj%C5%...). There is also a "debatable" connection of our system with a Kurosawa movie from the 50s (en.wikipedia.org/wiki/Rashomo...), but finding it is left as an exercise for the reader.

12.12.2024 03:11 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Plot showing the tail latency and goodput of Rajomon against several state of the art systems.

Plot showing the tail latency and goodput of Rajomon against several state of the art systems.

The expressiveness of our market-based scheme can provide significant benefits in the case of services that support a variety ๐Ÿ’ of input requests and deeper service graphs ๐Ÿ‹ Rajomon reduces tail latency by 78% and increases goodput by 45% against SOTA for high load!

12.12.2024 03:11 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0