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https://issues.apache.org/jira/browse/DRILL-6693?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16586273#comment-16586273
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Vlad Rozov commented on DRILL-6693:
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[~angozhiy] Did you verify that changing {{drill.exec.http.jetty.server.
selectors }} also changes number of jetty threads? Please attach jstack of a
drillbit with not default number of acceptors/selectors.
[~arina] DRILL-5994 configures drill to accept 2 concurrent requests. If this
is not the case, there may be a bug in DRILL-5994 implementation that needs to
be investigated. If by default drill handles 2 **concurrent** requests, the
behavior is by design drill should not be used as a web server. If it is
necessary to serve more than 2 concurrent requests, DRILL-5994 introduces
configuration parameters to manage how many concurrent requests (not session)
drillbit should be able to handle.
Note that jetty or any other web server design implies that long-running SQL
queries will be served asynchronously (similar to how requests are handled on
netty threads) if submitted over web interface as well. Jetty threads,
acceptors and selectors are limited resources (whether there are only 2 or a
100).
> 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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