Code search experiencing degraded performance

Incident update

Between 2026-02-23 19:10 and 2026-02-24 00:46 UTC, all lexical code search queries in GitHub.com and the code search API were significantly slowed, and during this incident, between 5 and 10% of search queries timed out. This was caused by a single customer who had created a network of hundreds of orchestrated accounts which searched with a uniquely expensive search query. This search query concentrated load on a single hot shard within the search index, slowing down all queries. After we identified the source of the load and stopped the traffic, latency returned to normal.<br /><br />To avoid this situation occurring again in the future, we are making a number of improvements to our systems, including: improved rate limiting that accounts for highly skewed load on hot shards, improved system resilience for when a small number of shards time out, improved tooling to recognize abusive actors, and capabilities that will allow us to shed load on a single shard in emergencies.