
Meta’s Bold Move: Ditching C for Rust in Messaging Infrastructure
2025-07-10
Author: Charlotte
Meta Revolutionizes Messaging with Rust
In a significant shift that could reshape its messaging infrastructure, Meta is transitioning from a cumbersome C codebase to the more modern Rust programming language. This change aims to improve maintainability and enhance developer satisfaction, a move discussed in detail during episode 76 of The Metatech Podcast by Meta's Messaging Infrastructure team.
Why Rust? The Driving Forces Behind the Migration
The transition isn't just about updating technology; it’s a strategic decision driven by three key factors: memory safety, long-term maintainability, and, most importantly, developer happiness. With billions of users relying on this core library across platforms like Facebook, Messenger, and Instagram daily, the stakes are high.
The Struggles of the Old Codebase
Meta engineers described the old C runtime as a tangled mess, with sprawling functions that often exceeded hundreds of lines and complicated manual memory management processes. Developers had to allocate variables at the beginning of a file—only to free them much later, making even minor code changes treacherous. As one engineer humorously labeled it, 'spaghetti begets spaghetti.'
Rust to the Rescue: Cleaner Code and Safer Development
Rust offers compile-time ownership checks that can eliminate many of the errors that plagued the old system. But beyond safety, the team emphasized the importance of day-to-day happiness in coding. With features like rustfmt for deterministic formatting and real-time feedback from Rust-Analyzer, developers can iterate faster and feel more confident in their changes.
Overcoming Challenges: A Team Effort
Although the learning curve for Rust can appear daunting, especially for those with little prior exposure—like the engineers who jokingly admitted they only recognized the 'crab logo'—the team successfully adapted through one-on-one walkthroughs and thorough code reviews. Meta’s open-code culture played a crucial role in this process; engaging with Rust working groups turned challenges into collaborative learning experiences.
Streamlining Operations: Enhanced Tooling
Recent tooling improvements mean that engineers can seamlessly navigate between C and Rust, setting breakpoints, debugging, and accessing fully symbolicated mobile crash logs—an efficiency boost that was unimaginable just months ago.
Looking Ahead: Growing Interest in Rust
With happier developers empowered to make safer and quicker changes, the Rust working group has galvanized interest among engineers throughout the organization. Though the long-term plans for full implementation remain under wraps, early indications show a rising eagerness to adopt Rust across Meta’s mobile platforms.