Queries in state "waiting to be closed" still hold ACID locks

Impala queries that are in state "Waiting to be closed" still keep the ACID transactions open (and hold locks).

From the documentation:
These queries are no longer executing, either because they encountered an error or because they have returned all of their results, but they are still active so that their results can be inspected. To free the resources they are using, they must be closed.

But the ACID-resources like transactions and locks should be freed as soon as possible, no need to wait for the client to invoke close() on the query handle.