Dan Zheng

Dan Zheng

Dan Zheng is a software engineer at Google DeepMind. His interests are the intersection of programming languages and machine learning.
Authored Publications
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    Resolving Code Review Comments with Machine Learning
    Alexander Frömmgen
    Peter Choy
    Elena Khrapko
    Pierre-Antoine Manzagol
    Marcus Revaj
    2024 IEEE/ACM 46th International Conference on Software Engineering: Software Engineering in Practice (ICSE-SEIP) (to appear)
    Preview abstract Code reviews are a critical part of the software development process, taking a significant amount of the code authors’ and the code reviewers’ time. As part of this process, the reviewer inspects the proposed code and asks the author for code changes through comments written in natural language. At Google, we see millions of reviewer comments per year, and authors require an average of ∼60 minutes active shepherding time between sending changes for review and finally submitting the change. In our measurements, the required active work time that the code author must devote to address reviewer comments grows almost linearly with the number of comments. However, with machine learning (ML), we have an opportunity to automate and streamline the code-review process, e.g., by proposing code changes based on a comment’s text. We describe our application of recent advances in large sequence models in a real-world setting to automatically resolve code-review comments in the day-to-day development workflow at Google. We present the evolution of this feature from an asynchronous generation of suggested edits after the reviewer sends feedback, to an interactive experience that suggests code edits to the reviewer at review time. In deployment, code-change authors at Google address 7.5% of all reviewer comments by applying an ML-suggested edit. The impact of this will be to reduce the time spent on code reviews by hundreds of thousands of engineer hours annually at Google scale. Unsolicited, very positive feedback highlights that the impact of ML-suggested code edits increases Googlers’ productivity and allows them to focus on more creative and complex tasks. View details
    Dynamic Inference of Likely Symbolic Tensor Shapes in Python Machine Learning Programs
    Koushik Sen
    International Conference on Software Engineering: Software Engineering in Practice (ICSE-SEIP)(2024) (to appear)
    Preview abstract In machine learning programs, it is often tedious to annotate the dimensions of shapes of various tensors that get created during execution. We present a dynamic likely tensor shape inference analysis that annotates the dimensions of shapes of tensor expressions with symbolic dimension values. Such annotations can be used for understanding the machine learning code written in popular frameworks, such as TensorFlow, PyTorch, JAX, and for finding bugs related to tensor shape mismatch. View details
    Effect Handlers and Choice-Based Learning in JAX
    Shangyin Tan
    Ningning Xie
    NeurIPS Machine Learning for Systems Workshop(2023)
    Preview abstract Choice-based learning is a programming paradigm for expressing learning system in terms of choices and losses. We explore a practical implementation of choice-based learning in JAX by combining two techniques in a novel way: algebraic effects and the selection monad. We describe the design and implementation of our library, explore its usefulness for real-world applications like hyperparameter tuning and deep reinforcement learning, and compare it with existing approaches. View details
    Preview abstract The execution behavior of a program often depends on external resources, such as program inputs or file contents, and so cannot be run in isolation. Nevertheless, software developers benefit from fast iteration loops where automated tools identify errors as early as possible, even before programs can be compiled and run. This presents an interesting machine learning challenge: can we predict runtime errors in a ``static'' setting, where program execution is not possible? Here, we introduce a real-world dataset and task for predicting runtime errors, which we show is difficult for generic models like Transformers. As an alternative, we develop an interpreter-inspired architecture with an inductive bias towards mimicking program executions, which models exception handling and ``learns to execute'' descriptions of the contents of external resources. Surprisingly, we show that the model can also predict the location of the error, despite being trained only on labels indicating the presence/absence and kind of error. In total, we present a practical and difficult-yet-approachable challenge problem related to learning program execution and we demonstrate promising new capabilities of interpreter-inspired machine learning models for code. View details
    Mutable Value Semantics
    Dimitri Racordon
    Dave Abrahams
    Brennan Saeta
    Journal of Object Technology, 21(2022)
    Preview abstract Mutable value semantics is a programming discipline that upholds the independence of values to support local reasoning. In the discipline’s strictest form, references become second-class citizens: they are only created implicitly, at function boundaries, and cannot be stored in variables or object fields. Hence, variables can never share mutable state. Unlike pure functional programming, however, mutable value semantics allows part-wise in-place mutation, thereby eliminating the memory traffic usually associated with functional updates of immutable data. This paper presents implementation strategies for compiling programs with mutable value semantics into efficient native code. We study Swift, a programming language based on that discipline, through the lens of a core language that strips some of Swift’s features to focus on the semantics of its value types. The strategies that we introduce leverage the inherent properties of mutable value semantics to unlock aggressive optimizations. Fixed-size values are allocated on the stack, thereby enabling numerous off-the-shelf compiler optimizations, while dynamically sized containers use copy-on-write to mitigate copying costs. View details
    Swift for TensorFlow: A portable, flexible platform for deep learning
    Brennan Saeta
    Marc Rasi
    Brad Larson
    Xihui Wu
    Parker Schuh
    Saleem Abdulrasool
    Aleksandr Efremov
    Dave Abrahams
    Chris Lattner
    Richard Wei
    MLSys(2021)
    Preview abstract Swift for TensorFlow is a deep learning platform that scales from mobile devices to clusters of hardware accelerators in data centers. It combines a language-integrated automatic differentiation system and multiple Tensor implementations within a modern ahead-of-time compiled language oriented around mutable value semantics. The resulting platform has been validated through use in over 30 deep learning models and has been employed across data center and mobile applications. View details