February service disruptions post-incident analysis

In late February, GitHub encountered multiple service interruptions totaling over eight hours due to unexpected database load variations and configuration issues within its mysql1 database cluster. These events highlighted the need for improved operational readiness, observability, and performance testing, particularly concerning ProxySQL's scalability and integration with other systems. As a result, GitHub implemented immediate changes such as data partitioning, which notably reduced load and queries on the mysql1 cluster. Additionally, the company is pursuing long-term strategies including auditing database reads, enhancing feature flag usage, completing functional partitioning, refining dashboards, and exploring further data partitioning and sharding opportunities to bolster scalability and reliability. These efforts aim to stabilize the platform and build capacity for future growth, ensuring trust and dependability for GitHub's users.