The way the code written single transactional block makes the calls to the database and as well to the sysdesis-server over http for various status information. In the case if the syndesis-server is not available or response to the http is slow, then the database connection is stuck and leads to other issues like failing the connection synchronization.

Also it looks there is high percentage of threads being used by OKHttp library and may not be releasing in timely manner.