java.lang.OutOfMemoryError: GC overhead limit exceeded

[syc87]

ReleaseStateUpdateService.updateReactively calls releaseRepository.findAll every 5 seconds.
When there are a lot of published releases, It's very easy to cause memory overflow.
Because PKG_JSON_STRING is a very large string.
Even if OOM not happen, The program will get slower and slower.

PS：I'm developing an ETL platform.I expect to be able to run more tasks on very cheap devices.
so I expanded a new appDeployer which is alows stream app to run in threads.