Garbage Collection Makes Rust Easier to Use: A Randomized Controlled Trial of the Bronze Garbage Collector

TL;DR

This study introduces Bronze, a library-based garbage collector for Rust, and demonstrates through a controlled trial that it significantly improves usability for complex aliasing tasks, reducing completion time.

Contribution

The paper presents Bronze, an optional garbage collector for Rust, and provides empirical evidence that it enhances usability for complex memory management tasks.

Findings

Bronze users completed aliasing tasks faster.

Bronze reduced task completion time from 12 to 4 hours.

Ownership and lifetimes are primary usability challenges in Rust.

Abstract

Rust is a general-purpose programming language that is both type- and memory-safe. Rust does not use a garbage collector, but rather achieves these properties through a sophisticated, but complex, type system. Doing so makes Rust very efficient, but makes Rust relatively hard to learn and use. We designed Bronze, an optional, library-based garbage collector for Rust. To see whether Bronze could make Rust more usable, we conducted a randomized controlled trial with volunteers from a 633-person class, collecting data from 428 students in total. We found that for a task that required managing complex aliasing, Bronze users were more likely to complete the task in the time available, and those who did so required only about a third as much time (4 hours vs. 12 hours). We found no significant difference in total time, even though Bronze users re-did the task without Bronze afterward. Surveys indicated that ownership, borrowing, and lifetimes were primary causes of the challenges that users faced when using Rust.