Sorabh Hamirwasia created DRILL-5897:
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Summary: Support Query Cancellation when WebConnection is closed
on client side both for authenticated and unauthenticated user's
Key: DRILL-5897
URL: https://issues.apache.org/jira/browse/DRILL-5897
Project: Apache Drill
Issue Type: Task
Components: Web Server
Reporter: Sorabh Hamirwasia
Today there is no session created (using cookies) for unauthenticated Webuser
whereas for authenticated user's session is created. Also when a user submits a
query then we wait until entire results is gathered on WebServer side and then
send the entire Webpage in the response (probably that's how ftl works).
For authenticated user's we only cancel the queries in-flight when the session
is invalidated (either by timeout or logout). However in absence of session we
do nothing for unauthenticated user's so once a query is submitted it will run
until it's failed or successful. The only way to explicitly cancel a query is
from profile page which will not work when profiles are disabled.
We should research more on if it's possible to get the underlying WebConnection
(not session) close event and cancel queries running as part of that connection
close event. Also since today we will wait for entire query to finish on
backend server and then send the response back, which is when a bad connection
is detected it doesn't makes sense to cancel at that point (there is 1:1
mapping between request and connection) since query is already completed.
Instead we can send header followed by batches of data (pagination) then we can
detect early enough if connection is valid or not and cancel the query in
response to that. More research is needed in this area along with knowledge of
Jetty on how this can be achieved to make our WebServer more performant.
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