User the sonar version7.9.1 (Enterprise EditionVersion 7.9.1 ), the cache didn't work

The project is c/c++ and i set the env variable like:
sonar.cfamily.cache.enabled=true
sonar.cfamily.cache.path=${WORKSPACE}/.sonar/zz

The cache folder can be created, but there is nothing cached in the folder.
What’s the root cause?
Another, if i want to cache java result, how to set the env variables?

Hello,

Analysis Cache is supported only for C/C++/Objective-C. The related documentation is here: https://docs.sonarqube.org/latest/analysis/languages/cfamily/. The same parameters don’t exist for Java.

Why do you need such a cache for Java? If you have performance problems with SQ 7.9.1, did you try the latest version (8.3 as of today)?

Thanks
Alex