[IMPALA-4488] Impala session times out prematurely - even if there is a running query

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Impala 2.6.0
• Fix Version/s: Impala 2.8.0
• Component/s: Backend, Clients
• Target Version: Impala 2.8.0
• Assignee: Henry Robinson
• Reporter: Miklos Szurap
• Created: 15/Nov/16 17:58
• Updated: 16/Mar/17 03:30
• Resolved: 28/Nov/16 18:24

Description

Setting --idle_session_timeout to a lower value (for example 60 seconds) may cause queries to fail (to be cancelled) with "Session expired due to inactivity".

Currently we are experiencing this only through 3rd party clients (through Cloudera Impala ODBC connector), impala-shell and Hue/Impala query editor works well.

On the ODBC client side the error message is

Oct 20 13:43:41 ERROR 3933976352 Statement::SQLExecDirectW: [Cloudera][ImpalaODBC] (110) Error while executing a query in Impala: [HY000] : Unknown error and could not get runtime log: Client session expired due to more than 60s of inactivity (last activity was at: 2016-10-20 13:42:33). 

Based on the Impala documentation running queries should not be killed because of the "idle session timeout":

The --idle_session_timeout option specifies the time in seconds after which an idle session is expired. A session is idle when no activity is occurring for any of the queries in that session, and the session has not started any new queries.

To reproduce:

1. Set --idle_session_timeout=60
2. Set up Cloudera Impala ODBC driver
3. Through a 3rd party ODBC client run a bigger query, lasting longer than the session timeout