v.21.8Improvement

Support for Dynamic Reloading of Config for Thread Pool Adjustment in Background Jobs

Support for dynamic reloading of config to change number of threads in pool for background jobs execution (merges, mutations, fetches). #25548 (Nikita Mikhaylov).
Added support for dynamic reloading of the configuration to change the number of threads in the pool responsible for executing background jobs such as merges, mutations, and fetches.

Why it matters

This feature enables ClickHouse administrators to adjust the number of threads dedicated to background task execution without restarting the server. It improves operational flexibility and resource management by allowing thread pool size changes on-the-fly to better handle workload variations.

How to use it

Modify the configuration file to update the number of threads in the background jobs execution pool, then trigger a dynamic config reload. The new thread count will be applied immediately without requiring a server restart.