Originally published at bitsar.net. Twelve pods, one Redis, and @Cacheable(sync = true) on the method. I read that as a protected endpoint. It coordinates callers inside one JVM, so a cold key was still twelve calls to the same slow dependency. This is what I found when I went looking for the clustered version of that annotation, why I think it does not exist, and what it took to build one. Source, benchmarks, the full parameter guide and nine open issues: github.com/BitanSarkar/coalesce-java.