September 2021 Summaries

We're excited to partner with OpenAI to start beta testing Codex-powered features across Replit, aiming to make programming easier for users, especially beginners, by providing explanations and insights into code through the Explain Code feature, which allows users to select code blocks and ask for explanations. The goal is to understand where AI can be useful on the programming journey, with plans to expand to other features such as explaining why code isn't working as expected or formatting code by conversation.

Replit has introduced CodeMirror as the new code editor for mobile devices, marking the start of a concentrated effort to enhance mobile development experiences. CodeMirror is designed to offer an excellent touchscreen interface and supports all essential features expected from a code editor, with plans to expand its capabilities further. This update aims to assist users without computer access in learning and creating projects, and Replit intends to extend CodeMirror to desktop platforms to ensure a consistent experience across all devices. The transition involves porting current desktop features to mobile, such as threads and debuggers, with a commitment to further advancements in mobile programming. The announcement also acknowledges the contributions of intern Anas Yahya and emphasizes Replit's open environment for impactful changes, encouraging those interested in improving mobile programming to join their team.

Earlier this year, a significant issue was discovered involving data loss for some users, where repls would either be empty or changes to files would not be saved after reloading. Initially addressed through unstructured bug fixes, the problem escalated in mid-July, prompting a comprehensive investigation that revealed longstanding bugs that were silently corrupting data, some of which were load-bearing and could not be fixed in isolation. The team initiated a structured approach to address the issue, involving reverting recent deployments, logging and monitoring data loss points, discarding corrupt data while salvaging what was possible, and ensuring no further corrupt data was persisted. This involved a detailed examination of the filesystem snapshotting process and tackling issues such as a bad interaction in Golang’s exec.Cmd and limited disk space, which caused truncated stdin/stdout without raising errors. By the end of July, solutions were implemented to prevent further data loss, and proactive steps were taken to enhance system robustness, resulting in faster and more responsive repls, especially in multiplayer settings. Key lessons learned included the critical importance of addressing data loss immediately, the value of measurement and logging before implementing improvements, and the opportunity to enhance systems once an issue is identified.

We've improved the Replit workspace for Kaboom, a popular JavaScript game engine. The updated workspace allows developers to iterate quickly without experiencing delays when running their code after editing. It also features helpful error reporting and support for NPM packages and TypeScript by default. Additionally, the new template comes with an integrated tutorial, autocomplete, and customizable HTML templates. Developers now have total control over which version of Kaboom they use, as well as access to a transparent dev server that can be customized or turned into a multiplayer game server. The workspace also includes an assets library and a migration guide to help developers transition from the previous version of Kaboom.

We've improved the speed of Replit by optimizing its infrastructure and code, allowing for faster editing and interaction in the workspace, as well as increased CPU resources and faster VMs for subscribers to our Teams and Hacker plans. By analyzing metrics and running repls in each environment, we're continually working to identify areas for improvement and address slow repl performance.