===== Srinidhi Nagendra, former PhD student at IRIF: the tester of distributed programs =====

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> // "These program [ed. distributed programs] form the backbone of many modern internet services. For example, they power large databases that store data in the cloud. In my thesis, I **introduce new techniques to find correctness bugs in distributed programs**." **[[https://www.srinidhin.com/|Srinidhi Nagendra]], former PhD student at IRIF.**//\\ **Link to his PhD thesis**: [[https://www.srinidhin.com/docs/Thesis.pdf|Automated testing of distributed protocol implementations]]

\\ ===Could you introduce yourself briefly?===

I'm [[https://www.srinidhin.com/|Srinidhi Nagendra]], and recently I completed a **Joint PhD in Computer Science** from Université Paris Cité (IRIF) and [[https://www.cmi.ac.in/|Chennai Mathematical Institute]]. During my PhD, I was supervised by [[https://www.lix.polytechnique.fr/~cenea/|Constantin Enea]] and [[https://www.cmi.ac.in/~mksrivas/|Mandayam Srivas]]. Prior to my PhD, I completed a Master of Science in Computer Science from Chennai Mathematical Institute, India.  

===How did you end up doing research? ===

I was initially trained as an engineer and **worked as a Software Developer** for a couple years. In trying to better understand the tools I was using and the algorithms I was implementing, I **developed an interest in further studies** which naturally led me to pursue research. In particular, I was **interested in algorithms and programs** that allowed **multiple computers to talk and co-ordinate**. 

===Could you explain, in few sentences, what is your thesis about?===

My thesis, titled "[[https://www.srinidhin.com/docs/Thesis.pdf|Automated testing of distributed protocol implementations]]", focuses on **ensuring the correctness of programs** that allow different computers (processes) to **coordinate and collectively solve a program** (distributed programs). These programs form the **backbone of many modern internet services**. For example, they **power large databases** that store data in the cloud. **Bugs** in distributed programs can be costly since they **cause downtimes in the internet services**. It is also **hard to implement the distributed programs correctly** due to the **complex nature of the underlying protocols**. In my thesis, I **introduce new techniques to find correctness bugs in distributed programs**, thereby **improving the reliability** of the services built on top of them.

===You study in your thesis the correctness of implementations using formal models. Could you explain what it is about?===

Distributed programs (implementations) follow rules defined by the distributed algorithm (model). There exists a large body of research that ensures the correctness of the model independent of the implementations. In my thesis, **I leverage existing work done on the model, combine it with existing techniques to develop new techniques**. I also show in the thesis that the **new techniques are more effective in finding bugs and helping improve the reliability of distributed programs**.  

===To test distributed implementations you propose three new approaches, Netrix, WaypointRL, and ModelFuzz: why those new ones and not others?===

These are new techniques aimed directly at **checking the correctness of the implementations**. In each new technique, I borrow from the literature **an existing approach that has not yet been applied to distributed programs and demonstrate their effectiveness**. [[https://arxiv.org/abs/2303.05893|Netrix]] - introduces unit testing for distributed programs, [[https://dl.acm.org/doi/10.1145/3689779|WaypointRL]] - leverages Reinforcement Learning to automatically explore all possible states, and [[https://arxiv.org/abs/2410.02307|ModelFuzz]] - introduces a novel guidance mechanism to fuzz test distributed programs.  

=== In which concrete circumstances could your work be applied on? ===

Demonstrating the new techniques resulted in novel tools that one can use to **test distributed programs**. The tools can be used to **effectively test new or existing implementations of distributed programs** - programs that power databases.   

=== Now that you defended your thesis, on what are you focusing on? ===

I have started a new journey as a **Post doctoral researcher** at [[https://www.mpi-sws.org/|Max Planck Institute for Software Systems]] working with [[https://people.mpi-sws.org/~rupak/|Rupak Majumdar]]. Together, we aim to **scale verification techniques such as Partial Order Reduction to verify Distributed programs**.