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Dynamic Ranking Code Deployment

1 post · Aug 2026

What this trail covers

Glean's search engine has evolved to enable dynamic deployment of ranking code without requiring server restarts. This is achieved by leveraging Java's dynamic class loading capabilities, remapping class names with release tags to allow multiple versions to coexist, and uploading JAR archives from Cloud Storage. This significantly reduces deployment times, enables more frequent releases, facilitates developer experimentation, and provides robust versioning and rollback support.

All Glean trails
  1. Incrementally deploying ranking code at GleanThis post details the implementation of a dynamic ranking code deployment system for Glean's search engine. The core innovation is the use of Java's dynamic class loading to load JAR archives from Cloud Storage without restarting the Index Server. To handle multiple versions of ranking code, class names are remapped to include release tags (e.g., `com.glean.ranking.release123.TermInfo`). This allows for more frequent releases (nightly for internal, weekly for customers), faster developer experimentation, and instant rollback via configuration changes. The system addresses challenges like initial JAR decoding latency (around 1 second) by using warmup requests and caching subsequent loads.