System Java code, using the druid connection pool, retrieve data from the remote postgresql database, timing error org. Postgresql. Util. PSQLException: An I/O error occurred while sending to the backend. The error number, every day is a few times, is 2, 3, one hundred times more

Database LOG HKT LOG: could not receive data from the client: No connection could be made because the target machine actively refused it.

Can't really understand what causes, for help