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https://issues.apache.org/jira/browse/LENS-619?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Himanshu Gahlaut updated LENS-619:
----------------------------------
    Description: 
This is the refined model after knowledge crunching:

Lens will always accept a new query from a user and put it in a scheduling 
queue for processing.
Next candidate query picked up from scheduling queue for processing will be 
launched only if all query launching constraints evaluated on candidate query 
and launched queries allows the candidate query to be launched, otherwise the 
candidate query will be added to waiting queries.

When any launched query is finished, a set of waiting query selectors will 
select next waiting queries eligible for scheduling. Intersection of result of 
all waiting query selectors will be added to scheduling queue for reprocessing.

At initialization, Query Launching Constraints will be configured using 
configuration values.

New Query Launching Constraints and Waiting Query Selectors can be added at run 
time, without rebuilding and deploying lens module.

Waiting Queries will be persisted across server restarts.

  was:
[June 23. 2015]: 
This is the refined model after knowledge crunching:

Lens will always accept a new query from a user and put it in a scheduling 
queue for processing.
Next candidate query picked up from scheduling queue for processing will be run 
only if a query running constraint evaluated on running queries and candidate 
query allows the candidate query to be run, otherwise the candidate query will 
be moved to waiting queries list.
When any running query is finished, result of evaluation of query constraint 
might change, waiting queries might become eligible to be run, hence waiting 
queries will be moved back to scheduling queue to be re-processed.

Waiting Queries will be persisted across server restarts.

[Initial thought] (Not in work): Fair Usage Policy for using Lens

After a user has used the lens system beyond fair usage policy, he will get 
lens features in degraded mode. 

One of the forms of fair usage policy could be that at any point in time only N 
queries can be present in RUNNING state for a user. 
If N queries of a user are in RUNNING state, then a new query submitted by same 
user will stay in QUEUED state until one of the N queries in RUNNING state have 
moved to SUCCESSFUL, FAILED, OR CANCELLED state.


> Applying Query Launching Constraints before allowing a query to be launched
> ---------------------------------------------------------------------------
>
>                 Key: LENS-619
>                 URL: https://issues.apache.org/jira/browse/LENS-619
>             Project: Apache Lens
>          Issue Type: New Feature
>            Reporter: Himanshu Gahlaut
>            Assignee: Himanshu Gahlaut
>
> This is the refined model after knowledge crunching:
> Lens will always accept a new query from a user and put it in a scheduling 
> queue for processing.
> Next candidate query picked up from scheduling queue for processing will be 
> launched only if all query launching constraints evaluated on candidate query 
> and launched queries allows the candidate query to be launched, otherwise the 
> candidate query will be added to waiting queries.
> When any launched query is finished, a set of waiting query selectors will 
> select next waiting queries eligible for scheduling. Intersection of result 
> of all waiting query selectors will be added to scheduling queue for 
> reprocessing.
> At initialization, Query Launching Constraints will be configured using 
> configuration values.
> New Query Launching Constraints and Waiting Query Selectors can be added at 
> run time, without rebuilding and deploying lens module.
> Waiting Queries will be persisted across server restarts.



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