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From "Joe McDonnell (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-6232: Disable file handle cache by default
Date Tue, 05 Dec 2017 17:26:18 GMT
Hello Thomas Tauber-Marshall, Lars Volker, Tim Armstrong, 

I'd like you to reexamine a change. Please visit

to look at the new patch set (#4).

Change subject: IMPALA-6232: Disable file handle cache by default

IMPALA-6232: Disable file handle cache by default

There are scenarios where HDFS file appends or HDFS file
overwrites can lead to HDFS disabling short circuit reads.
Since this can be a performance regression, this changes
the default value for max_cached_file_handles to 0 to
disable the file handle cache by default. This also changes
the default value for unused_file_handle_timeout_sec to 270.
If users enable the file handle cache, this setting will
prevent some of the scenarios that disable short circuit

Ran existing file handle cache tests to verify that there
is no impact.

Change-Id: Iea7f943f63b72b42286a9e8b9987308baa79d7b0
M be/src/runtime/io/
1 file changed, 8 insertions(+), 2 deletions(-)

  git pull ssh:// refs/changes/50/8750/4
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Iea7f943f63b72b42286a9e8b9987308baa79d7b0
Gerrit-Change-Number: 8750
Gerrit-PatchSet: 4
Gerrit-Owner: Joe McDonnell <>
Gerrit-Reviewer: Joe McDonnell <>
Gerrit-Reviewer: Lars Volker <>
Gerrit-Reviewer: Thomas Tauber-Marshall <>
Gerrit-Reviewer: Tim Armstrong <>

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