Quanlong Huang has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/14846 )

Change subject: IMPALA-9195: Using multithreaded execution to accelerate 'show 
tables/databases'
......................................................................


Patch Set 11:

(8 comments)

This patch looks good to me! Leave some comments about error handling and nits.

http://gerrit.cloudera.org:8080/#/c/14846/11/be/src/common/global-flags.cc
File be/src/common/global-flags.cc:

http://gerrit.cloudera.org:8080/#/c/14846/11/be/src/common/global-flags.cc@306
PS11, Line 306: A value of 1 disables multi-threaded execution for checking 
authorization.
It may worth to mention that when set larger than 1, the parallism of FE 
requests may be limit by this. So the admin won't set this to 2 or 3 hoping 
SHOW statements get 2-3 times speed-up.


http://gerrit.cloudera.org:8080/#/c/14846/11/fe/src/main/java/org/apache/impala/service/Frontend.java
File fe/src/main/java/org/apache/impala/service/Frontend.java:

http://gerrit.cloudera.org:8080/#/c/14846/11/fe/src/main/java/org/apache/impala/service/Frontend.java@202
PS11, Line 202: 32
I think 32 is not large enough since the default value of fe_service_threads is 
64. So there're at most 128 parallel requests (64 for beeswax, 64 for hs2). 
Maybe 128 is more reasonable. Looks like no harm to set it larger.


http://gerrit.cloudera.org:8080/#/c/14846/11/fe/src/main/java/org/apache/impala/service/Frontend.java@806
PS11, Line 806:     /* dbName and user cannot be null, tblName and owner can be 
null. */
Method comments start by '/**', end by '*/' and explain what the method does. 
This seems not a method comment. Maybe put it inside the method?


http://gerrit.cloudera.org:8080/#/c/14846/11/fe/src/main/java/org/apache/impala/service/Frontend.java@854
PS11, Line 854:
nit: don't need space


http://gerrit.cloudera.org:8080/#/c/14846/11/fe/src/main/java/org/apache/impala/service/Frontend.java@856
PS11, Line 856:
nit: don't need space


http://gerrit.cloudera.org:8080/#/c/14846/11/fe/src/main/java/org/apache/impala/service/Frontend.java@857
PS11, Line 857:
nit: don't need space


http://gerrit.cloudera.org:8080/#/c/14846/11/fe/src/main/java/org/apache/impala/service/Frontend.java@857
PS11, Line 857:         LOG.error("Encountered an error checking access" , e);
Should we break the loop in this case?


http://gerrit.cloudera.org:8080/#/c/14846/11/tests/authorization/test_authorization.py
File tests/authorization/test_authorization.py:

http://gerrit.cloudera.org:8080/#/c/14846/11/tests/authorization/test_authorization.py@674
PS11, Line 674: test_sentry_show_stmts_with_any
It'd be better to use another log folder. This is used in a previous test.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I860e0d18afa0421665f8b3b1c5561d6bdacc5e96
Gerrit-Change-Number: 14846
Gerrit-PatchSet: 11
Gerrit-Owner: Zhou Xu <[email protected]>
Gerrit-Reviewer: Csaba Ringhofer <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Quanlong Huang <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Reviewer: Vihang Karajgaonkar <[email protected]>
Gerrit-Reviewer: Zhou Xu <[email protected]>
Gerrit-Comment-Date: Tue, 24 Dec 2019 06:44:22 +0000
Gerrit-HasComments: Yes

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