Engineering

We serve a lot of diffs here at GitHub. Because it is computationally expensive to generate and display a diff, we’ve traditionally had to apply some very conservative limits on…

Over the last year we’ve developed our new load balancer, called GLB (GitHub Load Balancer). Today, and over the next few weeks, we will be sharing the design and releasing its components as open source software.

Spokes is the replication system for the file servers where we store over 38 million Git repositories and over 36 million gists.It keeps at least three copies of every repository…

At GitHub we use MySQL as our main datastore. While repository data lies in git, metadata is stored in MySQL. This includes Issues, Pull Requests, Comments etc. We also auth…

GitHub hosts a wide range of user content, and like all large websites this often causes us to become a target of denial of service attacks. Around a year ago,…

We shipped subresource integrity a few months back to reduce the risk of a compromised CDN serving malicious JavaScript. That is a big win, but does not address related content…

Edit: DGit is now called Spokes GitHub hosts over 35 million repositories and over 30 million Gists on hundreds of servers. Over the past year, we’ve built DGit, a new…

GitHub.com no longer delivers its icons via icon font. Instead, we’ve replaced all the Octicons throughout our codebase with SVG alternatives. While the changes are mostly under-the-hood, you’ll immediately feel…

Anyone who has worked on a large enough codebase knows that technical debt is an inescapable reality: The more rapidly an application grows in size and complexity, the more technical…

At GitHub we place an emphasis on stability, availability, and performance. A large component of ensuring we excel in these areas is deploying services on bare-metal hardware. This allows us…

Looking through our exception tracker the other day, I ran across a notice from our slow-query logger that caught my eye. I saw a SELECT … WHERE … LIKE query…

At GitHub we have a lot of software running our product and company. We also have a lot of potential contributing members. Being able to get from git clone to…

At GitHub, we use a variant of the Flow pattern to deploy changes: new code is always deployed from a pull request branch, and merged only once it has been…

Earlier this spring, we upgraded our database cluster to MySQL 5.6. Along with many other improvements, 5.6 added some exciting new features to the performance schema. MySQL’s performance schema is…

Believe it or not, just over a year ago, GitHub Pages, the documentation hosting service that powers nearly three-quarters of a million sites, was little more than a 100-line shell…