Joe McDonnell has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/11959 )

Change subject: IMPALA-7804: Mitigate s3 consistency issues for test_scanners
......................................................................


Patch Set 2:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/11959/2//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/11959/2//COMMIT_MSG@27
PS2, Line 27: This may improve the
            : likelihood that the filesystem is consistent by
            : the time we read it.
> The docs at https://docs.aws.amazon.com/AmazonS3/latest/dev/Introduction.ht
Based on the s3 tracing, we always do an existence check before we do a write. 
This puts us in the eventually consistent case. I think one thing we can do if 
we know the destination won't exist is to get rid of the existence check. That 
should change us over to read-after-write consistency.

S3 tests are definitely going to need more than this change. I'm interested in 
trying out S3Guard. I haven't tested it, so I'm not sure whether it fixes this 
issue. S3Guard looks like it helps for listing directories, but we're actually 
trying to read the file. We'll see if it helps. There might be further changes 
to read our writes and wait for consistency.


http://gerrit.cloudera.org:8080/#/c/11959/2/tests/common/file_utils.py
File tests/common/file_utils.py:

http://gerrit.cloudera.org:8080/#/c/11959/2/tests/common/file_utils.py@67
PS2, Line 67: command
> nit: introducing 'command' variable seems unnecessary, and we don't do that
You're right, there's no need. I think this came about from an earlier version 
where I was trying to work around a long line (which is now no longer long). 
Fixed.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Id042496beabe0d0226b347e0653b820fee369f4e
Gerrit-Change-Number: 11959
Gerrit-PatchSet: 2
Gerrit-Owner: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]>
Gerrit-Comment-Date: Tue, 20 Nov 2018 21:01:43 +0000
Gerrit-HasComments: Yes

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