Thymeleaf & Spring MVC: Can live template edits propagate across rolling instances during zero‑downtime migration?

Goal

Upgrade a small Spring MVC application to a new Thymeleaf version while keeping the service available. The objective is to deploy the new template engine without a full restart, ensuring that all users receive consistent views during the transition.

Constraints & Uncertainty

Thymeleaf caches parsed templates by default in Spring Boot production mode. When a template file is modified, the change is not seen by existing instances until the cache is evicted or the JVM restarts. Rolling restarts can leave a mix of old and new instances, each potentially holding different template versions or dialects. Mixing StandardDialect with SpringStandardDialect across instances can cause rendering errors. Spring Boot devtools can disable caching and enable live reload, but it is intended for development and may introduce performance overhead in production.

Unresolved Decision

Is there a supported, production‑grade approach to force a live cache refresh across all instances during a rolling deployment, or must the migration accept a brief period of inconsistent rendering?

Specific Questions

• What configuration changes or API calls can invalidate Thymeleaf’s template cache on a running instance without a full JVM restart, and can these be triggered automatically during a rolling update?
• If different instances run different Thymeleaf dialects during migration, what is the impact on template rendering, and how can we guarantee that shared templates render identically across the cluster?