v.21.11Improvements

Fix lock-order inversion in periodic dictionary and config reload

Fix lock-order-inversion between periodic dictionary reload and config reload. #29928 (Azat Khuzhin).
Fixes a lock order inversion issue between periodic dictionary reload and configuration reload processes in ClickHouse.

Why it matters

This fix addresses a potential deadlock problem caused by the improper lock order when periodic dictionary reloads and configuration reloads occur concurrently. Resolving this improves stability and reliability of dictionary and configuration management.

How to use it

The fix is applied internally in the ClickHouse server code and requires no user action. Users will benefit from improved stability after upgrading to the version including this fix.