Joe McDonnell has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/9371 )

Change subject: IMPALA-6549: Enable file handle cache by default
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Patch Set 1:

(1 comment)

> (1 comment)
 >
 > Do you have a list of tests you plan to run?

I ran core tests with no issues. This will get incorporated into the next run 
of performance tests. Separately, I plan to do a warmup test where I run with a 
table with a large number of files with a cold cache.

Since remote files don't participate in the cache, I don't forsee any issues 
with S3 or other platforms.

http://gerrit.cloudera.org:8080/#/c/9371/1/be/src/runtime/io/disk-io-mgr.cc
File be/src/runtime/io/disk-io-mgr.cc:

http://gerrit.cloudera.org:8080/#/c/9371/1/be/src/runtime/io/disk-io-mgr.cc@109
PS1, Line 109: 21600
> how was that chosen?
This is a good point. The concern for aging out file handles was about disk 
space getting freed up. This is controlled by the fs.trash.interval. We wanted 
the eviction time to be less than the typical fs.trash.interval so that the 
disk space usage would not be impacted by the cache. This is reverting back to 
what we originally merged in IMPALA-5352.

I checked some Cloudera deployments, and they default to 1 day for 
fs.trash.interval. HDP has a default of 6 hours. I think there is a range of 
appropriate defaults.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I6935825a1c4c7b2da0bb877f732027be1a57a8b7
Gerrit-Change-Number: 9371
Gerrit-PatchSet: 1
Gerrit-Owner: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Dan Hecht <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins
Gerrit-Reviewer: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Lars Volker <[email protected]>
Gerrit-Comment-Date: Thu, 22 Feb 2018 00:05:09 +0000
Gerrit-HasComments: Yes

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