Connection timeouts can't be processed if a query is running.

[juanjux]

Connection timeouts from Vitess doesn't trigger, and thus stop the query, is a query is running but not sending anything. This is because query processing and the Handler run on the same thread, so when Vitess detects a timeout the call to CloseConnection can't be processed until the query finishes.

Related to: https://github.com/src-d/gitbase-spark-connector-enterprise/issues/81

[erizocosmico]

Fix to this was already merged at #801