IHEII

[Bug]: test_aggregation_empty_table

2

**Describe the bug** Can not pass test_aggregation_empty_table test in 3.2.4. Empty results will be returned when users aggregate in an empty table. We return a CommonError, which is not the...

**Enhancement** There are serval problems in rpc::Connection garbage collection now. 1. ``Connection::cancel_requests()`` duplicated used 2. ``Connection.active`` is useless 3. Another way to close the ConnectionSender/Reader/Connection **gracefully**. The reason why we...