[jira] [Commented] (DRILL-6693) When a query is started from Drill Web Console, the UI becomes inaccessible until the query is completed

["Kunal Khatua (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-6693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16584325#comment-16584325 ] 

Kunal Khatua commented on DRILL-6693:
-------------------------------------

I suspect that the Drillbit's JVM is busy holding the resultSet in heap memory and then using additional heap memory to convert it into a JSON object. If you are able to monitor the JVM heap before you start the query, it most likely is hitting the limit. That forces the JVM to pause and attempt garbage collection.

DRILL-6477 tries to mitigate this problem by failing the query if we come close to the GC limit.

> When a query is started from Drill Web Console, the UI becomes inaccessible until the query is completed
> --------------------------------------------------------------------------------------------------------
>
>                 Key: DRILL-6693
>                 URL: https://issues.apache.org/jira/browse/DRILL-6693
>             Project: Apache Drill
>          Issue Type: Bug
>    Affects Versions: 1.13.0, 1.14.0, 1.15.0
>            Reporter: Anton Gozhiy
>            Priority: Major
>
> *Steps:*
>  # From Web UI, run the following query:
> {noformat}
> select * 
> from (
>     select employee_id, full_name, first_name, last_name, position_id, position_title, store_id, department_id, birth_date, hire_date, salary, supervisor_id, education_level, marital_status, gender, management_role 
>     from cp.`employee.json` 
>     union
>     select employee_id, full_name, first_name, last_name, position_id, position_title, store_id, department_id, birth_date, hire_date, salary, supervisor_id, education_level, marital_status, gender, management_role 
>     from cp.`employee.json` 
>     union
>     select employee_id, full_name, first_name, last_name, position_id, position_title, store_id, department_id, birth_date, hire_date, salary, supervisor_id, education_level, marital_status, gender, management_role
>     from cp.`employee.json`)
> where last_name = 'Blumberg'
> {noformat}
>  # While query is running, try open the Profiles page (or any other). If It completes too fast, add some unions to the query above.
> *Expected result:*
>  Profiles page should be opened. The running query should be listed.
> *Actual result:*
>  The Web UI hangs until the query completes.
> *Notes:*
> - If you open another tab with Web Console, it also stuck when the query is running.
> - If the query is started from sqlline, everything is fine.



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