[LENS-777] Query remains in queue even when driver is free

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.4
• Assignee: Akshay Goyal
• Reporter: Arshad Matin
• Created: 17/Sep/15 11:09
• Updated: 05/Nov/15 18:01
• Resolved: 23/Sep/15 12:09

Description

Scenario:

Config

  <property>
    <name>driver.max.concurrent.launched.queries</name>
    <value>1</value>
    <description>Maximum queries which can be launched simultaneously on this driver. This should be equal to
      lens.driver.jdbc.pool.max.size. This configuration value is only useful when MaxConcurrentDriverQueriesConstraint
      is enabled by using org.apache.lens.server.api.query.constraint.MaxConcurrentDriverQueriesConstraintFactory as
      one of the factories in lens.driver.jdbc.query.constraint.factories property.</description>
  </property>
<property>
    <name>lens.driver.jdbc.pool.max.size</name>
    <value>1</value>
    <description>Maximum number of concurrent connections allowed in pool</description>
  </property>

Launched 1st query with user U1
Launched 2nd query with user U2
Launched 3rd query with user U1
Launched 4th query with user U2

Query Status
==========
Q1 -> Running
Q2 -> Queued(queue number = 1)
Q3 -> Queued(queue number = 2)
Q4 -> Queued(queue number = 3)

When Q1 completes, Query Status
==========================
Q1 -> Successful
Q2 -> Queued(queue number = 1)
Q3 -> Running
Q4 -> Queued(queue number = 2)

When Q2 completes, Query Status
==========================
Q1 -> Successful
Q2 -> Queued(queue number = 1)
Q3 -> Successful
Q4 -> Queued(queue number = 2)

user "U2" query will never get picked. Another query launched by user "U1" will be answered.

Issue Links

• links to: Review Request