Rohan Padhye
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rohan.padhye.org
Rohan Padhye
@rohan.padhye.org
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Computer Science professor at CMU. Doing research on automated software testing and bug finding. https://rohan.padhye.org
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rohan.padhye.org
Excited to announce that the Fray paper has been accepted to OOPSLA'25! Work led by @aoli.al with a full pastalab.org collaboration.

📄: rohan.padhye.org/files/fray-o...
💻: github.com/cmu-pasta/fray
🎥: www.youtube.com/watch?v=AX6P...
Front page of a paper titled "Fray: An Efficient General-Purpose Concurrency Testing Platform for the JVM" by Ao Li et al. from Carnegie Mellon University.
August 28, 2025 at 2:51 PM
rohan.padhye.org
Just Accepted to ACM TOSEM!

The "Havoc Paradox" is about the relationship between byte-level fuzzer mutations and their effect on the inputs produced by generators for structured strings (e.g. XML/SQL). Can disruptive mutations be controlled? Should they be? Find out.

📄 dl.acm.org/doi/pdf/10.1...
June 6, 2025 at 7:02 PM
rohan.padhye.org
We also have an excellent program of research talks and *fuzzing nuggets*. Detailed schedule coming soon.

conf.researchr.org/home/issta-2...
List of Accepted Papers at the FUZZING Workshop
May 27, 2025 at 6:49 PM
rohan.padhye.org
We're excited to announce two keynote speakers for the #FUZZING'25 workshop (part of @issta_conf at Trondheim, Norway):

[*] Will Wilson, CEO and Co-Founder of Antithesis
[*] Miryung Kim, Professor and Vice Chair of Graduate Studies at UCLA

conf.researchr.org/home/issta-2...
May 27, 2025 at 6:49 PM
rohan.padhye.org
Love this argument: prior work does not use our novel idea.
Text highlighted from a research paper that says "To the best of our knowledge, there is no existing search-based testing approach for productiongrade AV software, including [20], [21], [41]–[55] that: (i) uses our novel gene representation"
March 31, 2025 at 2:43 PM
rohan.padhye.org
Happy Daylight Savings Time to everyone in the US! A few more weeks for European Summer Time.

If you notice some of your apps glitching, don't be alarmed. Even ChatGPT can't write correct date/time code!!!

See more in our upcoming paper: rohan.padhye.org/files/dateti... (MSR'25 preprint)
Paper titled "It’s About Time: An Empirical Study of Date and Time Bugs in Open-Source Python Software". Authors List: Shrey Tiwari Carnegie Mellon University Pittsburgh, PA, USA shrey@cmu.edu Peter Vandervelde∗ University of California, Santa Barbara Santa Barbara, CA, USA pvandervelde@ucsb.edu Serena Chen∗ University of California, San Diego San Diego, CA, USA sec022@ucsd.edu Ao Li Carnegie Mellon University Pittsburgh, PA, USA aoli@cmu.edu Alexander Joukov∗ Stony Brook University Stony Brook, NY, USA ajoukov@cs.stonybrook.edu Rohan Padhye Carnegie Mellon University Pittsburgh, PA, USA rohanpadhye@cmu.edu
March 10, 2025 at 1:37 PM
rohan.padhye.org
Back to basics: Concurrency testing in Java!

Our new tool *Fray* correctly solves a 25+ year old problem for real-world software. See this feature from Elastic Labs about Fray's contributions to Lucene.

📰: www.elastic.co/search-labs/...

🔧: github.com/cmu-pasta/fray

📝: arxiv.org/pdf/2501.12618
Blog post titled "Concurrency bugs in Lucene: How to fix optimistic concurrency failures" By Benjamin Trent and Ao Li (February 7, 2025) Text reads: "Thanks to Fray, a deterministic concurrency testing framework from CMU’s PASTA Lab, we tracked down a tricky Lucene bug and squashed it"
February 7, 2025 at 9:57 PM
rohan.padhye.org
[3/3] Another similarly cool idea is "events" in Tyche (by @harrisongoldste.in et al.), which is a PBT visualization extension for VSCode. We've actually integrated Tyche into JQF now so it works with Java fuzzing! Check it out.

(Ref: github.com/tyche-pbt/ty..., github.com/rohanpadhye/...)
A screenshot with two columns. On the left, a Python property-based test annotated with `event(<predicate>)` statements. On the right, a visualization of how frequently event predicates have been excercised by random tests, plotted as histograms and tree-maps.
December 13, 2024 at 4:38 PM
rohan.padhye.org

[2/3] I like the "Sometimes Assertions" abstraction recommended by Antithesis, which generalizes code coverage to user-defined predicates, possibly interleaved with application logic. Maybe we should support these in JQF too.

(Ref: antithesis.com/docs/best_pr...)
You may be less familiar with the second type of assertion, which at Antithesis we call Sometimes Assertions. Just as an always assertion asserts that something is always true, a Sometimes Assertion asserts that something is sometimes true! Here are some examples: ``` assertSometimes x < 1; assertSometimes y == 1; assertSometimes(condition); ```
December 13, 2024 at 4:38 PM
rohan.padhye.org
How do you know whether random testing is working as expected?

[1/3] Long ago in JQF, we used `assumeTrue` to bias fuzzing towards *valid* inputs. This is powerful, but the abstraction is quite coarse if you have many properties.

(Refs: github.com/rohanpadhye/..., rohan.padhye.org/files/zest-i...)
``` @Fuzz public void testMap2Trie(Map<String, Integer> map, String key) { assumeTrue(map.containsKey(key)); // Create new trie with input `map` Trie trie = new PatriciaTrie(map); // The key should exist in the trie as well assertTrue(trie.containsKey(key)); } ```
December 13, 2024 at 4:38 PM