Inside GitHub’s new Git storage architecture
The GitHub Blog · 软件开发
Last week at GitHub Universe, we announced our new Git storage architecture, capable of handling thousands of writes per second with reads that scale on demand. Through internal testing, we’ve demonstrated the ability to support 5,000 concurrent agents working on a repository, sending 7,200 pushes per second to a repo, all while serving read traffic with consistently low latency. This new architecture is the foundation for GitHub to support agentic development for hundreds of millions of developers, and we’ve been building it underneath GitHub while it keeps running. Over the past year, agents changed what a busy repository looks like on GitHub. In our first post in this series, we laid out the two principles behind our next-generation Git storage architecture: minimize coordination, and decouple storage from compute. In our last post , we covered the bridge: moving 99.99999% of repositories into Azure, scoping the write quorum to individual references, and standing up virtual replicas backed by Azure Blob Storage. We also left off with an observation: very little of a write needs to be ordered. Git objects are immutable and named by their contents, meaning two writers can store them at the same time without agreeing on anything. The part of a push that needs agreement is the reference update, and a reference update is tiny in comparison. Virtual replicas were the first step toward building around that, and the means by which we onboard repositories to the new architecture. The rest of the architecture builds on that observation. Only reference updates need agreement. That lets the parts of Git infrastructure that used to be tightly coupled (storing data, serving requests, and maintaining repositories) scale independently. For developers, Git stays Git: they push, fetch, and branch the same way, with the same protections in place. Below, we walk through the requirements behind the design, follow a request through the system, and dive deep into two of its components.