Quanlong Huang has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/21803 )

Change subject: IMPALA-915: Support cancel queries during planning
......................................................................


Patch Set 14:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/21803/12/tests/webserver/test_web_pages.py
File tests/webserver/test_web_pages.py:

http://gerrit.cloudera.org:8080/#/c/21803/12/tests/webserver/test_web_pages.py@1085
PS12, Line 1085:     delay_created_action = 
"impalad_load_tables_delay:SLEEP@5000"
> I've tried these and see no evidence they're actually used.
They are used in metadata loading/reloading, e.g. in REFRESH. I saw an 
unexpected behavior when playing with these.
Start the cluster in local-catalog mode:
bin/start-impala-cluster.py --catalogd_args=--catalog_topic_mode=minimal 
--impalad_args=--use_local_catalog

Run a slow REFRESH (took 1m50s):
impala-shell.sh
default> set debug_action=catalogd_refresh_hdfs_listing_delay:SLEEP@300;
default> refresh tpcds.store_sales;

Run a DESCRIBE on another impalad:
impala-shell.sh -i localhost:21051
default> describe tpcds.store_sales;

Tried cancelling the DESCRIBE statement, the browser is hanging. Tried refresh 
the brower page and cancel the query again. Got an error of "Error: Invalid or 
unknown query handle:".

BTW, I can cancel the REFRESH statement. But it's shown in the "waiting to be 
closed" list and the operation is still on-going in catalogd side, shown in the 
"/operations" WebUI of catalogd.

When queries are stuck in CREATED state, there are usually something wrong or 
super slow in metadata loading in catalogd side. Users might expect the catalog 
operations be cancelled as well to recover the cluster from a crazy state.

Anyway, the current patch is already a good improvement. I'm ok to support 
cancelling catalog operations in a follow-up task. Maybe just fix the issue of 
cancelling DESCRIBE failed.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I0d25d4c7fb0b8dcc7dad9510db1e8dca220eeb86
Gerrit-Change-Number: 21803
Gerrit-PatchSet: 14
Gerrit-Owner: Michael Smith <[email protected]>
Gerrit-Reviewer: Andrew Sherman <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Jason Fehr <[email protected]>
Gerrit-Reviewer: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Michael Smith <[email protected]>
Gerrit-Reviewer: Quanlong Huang <[email protected]>
Gerrit-Comment-Date: Mon, 18 Nov 2024 08:03:07 +0000
Gerrit-HasComments: Yes

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