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From "Marcel Kornacker (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-4623: Enable file handle cache
Date Wed, 10 May 2017 20:48:39 GMT
Marcel Kornacker has posted comments on this change.

Change subject: IMPALA-4623: Enable file handle cache

Patch Set 6:


quick comments
File be/src/exec/

Line 92:       initial_ranges_issued_(false),
you can also initialize that inline in the .h file
File be/src/runtime/disk-io-mgr-handle-cache.h:

Line 105:     std::unique_ptr<HdfsFileHandle> fh_;
no trailing _ for structs
File be/src/runtime/disk-io-mgr-handle-cache.h:

Line 116:     MapType cache_;
provide comments for variables, in particular invariants (e.g., it looks like the lru list
only contains unused handles)
File be/src/runtime/disk-io-mgr-handle-cache.inline.h:

Line 33:   if (hdfs_file_ != nullptr && fs_ != nullptr) {
could these be null?
File be/src/runtime/disk-io-mgr-handle-cache.inline.h:

Line 61:   int index = hash<string>()(key) % NUM_PARTITIONS;
also: use something out of util/hash-util.h
File be/src/runtime/

Line 1309
> I use this as the key for the map, so switching the hash alone wouldn't eli
probably a good idea, it's unlikely that we'll see a lot of overwritten files.

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Gerrit-MessageType: comment
Gerrit-Change-Id: Ibe5ff60971dd653c3b6a0e13928cfa9fc59d078d
Gerrit-PatchSet: 6
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Joe McDonnell <>
Gerrit-Reviewer: Dan Hecht <>
Gerrit-Reviewer: Joe McDonnell <>
Gerrit-Reviewer: Marcel Kornacker <>
Gerrit-Reviewer: Tim Armstrong <>
Gerrit-HasComments: Yes

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