We recently upgraded Impala from 2.14 to 3.2. The same code that was running against 2.14 is now running into Connection timeout errors with lots of open sessions shown in the coordinator node Web UI. We added idle-session-timeout to impalad startup in hopes that would clean out idle sessions but it only seems to mark them as expired but does not close them. After a couple hours of moderate use of our system attempts to make JDBC connections start timing out. Closing the idle sessions manually through the Web UI doesn't seem to solve the problem. Only a restart of the coordinator nodes seems to allow the client to create connections again.
We have upgraded the JDBC driver to ClouderaIimpalaJDBC41-220.127.116.113 hoping that would help fix the issue but it doesn't seem to have improved any.