Tim Armstrong has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/16856 )

Change subject: IMPALA-10375: Lock down which filesystems use the file handle 
cache
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Patch Set 1:

(1 comment)

I suggested a refactoring, it would make the patch a bit bigger but might pay 
off. LMK what you think.

http://gerrit.cloudera.org:8080/#/c/16856/1/be/src/runtime/io/scan-range.cc
File be/src/runtime/io/scan-range.cc:

http://gerrit.cloudera.org:8080/#/c/16856/1/be/src/runtime/io/scan-range.cc@200
PS1, Line 200:   if (is_file_handle_caching_enabled() && 
filesystem_supports_handle_caching(file()) &&
I was originally thinking about this from the point of view of performance 
overhead and mostly convinced myself that the extra string parsing wouldn't add 
much.

But it occurs to me that the code would probably be simplified overall if we 
figured out the filesystem implementation once per scan range, i.e. at the same 
time as AssignDiskQueue() is called. We could convert it to an enum like FsType 
in the frontend these disk_id/filename checks in ScanRange would be a bit less 
ad-hoc.


I think that would make handling 
https://issues.apache.org/jira/browse/HDFS-15289 simpler too once we get to 
that.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I136c3da9d19590cdbe8623d22480b8dd07192ce3
Gerrit-Change-Number: 16856
Gerrit-PatchSet: 1
Gerrit-Owner: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Comment-Date: Fri, 11 Dec 2020 05:16:48 +0000
Gerrit-HasComments: Yes

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