Joe McDonnell has posted comments on this change.

Change subject: IMPALA-4623: Enable file handle cache
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Patch Set 15:

(5 comments)

http://gerrit.cloudera.org:8080/#/c/6478/15/be/src/runtime/disk-io-mgr-scan-range.cc
File be/src/runtime/disk-io-mgr-scan-range.cc:

Line 283:     if (exclusive_hdfs_fh_ != nullptr) return Status::OK();
> when will this be true?
The IO thread is calling ReadRange on each ScanRange. ReadRange calls Open 
whether or not that ScanRange was already open. This check short-circuits in 
the case that the ScanRange was already open.


Line 351:       VLOG_FILE << "Cache HDFS file handle file=" << file();
> this is not a meaningful log message, let's remove it
Removed.


Line 420:     HdfsFileHandle* hdfs_file_from_cache = nullptr;
> the name is somewhat misleading, because exclusive_hdfs_fh_ is still from t
Changed to "borrowed_hdfs_fh"


Line 484:         // - or if the file handle is not from the cache
> but exclusive_hdfs_fh_ is also from the cache, why wouldn't we retry in tha
Changed to do retry for exclusive file handles.


http://gerrit.cloudera.org:8080/#/c/6478/15/be/src/runtime/disk-io-mgr.cc
File be/src/runtime/disk-io-mgr.cc:

Line 1271:   bool cache_hit;
> rename to dummy or something like that
Done


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ibe5ff60971dd653c3b6a0e13928cfa9fc59d078d
Gerrit-PatchSet: 15
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Dan Hecht <[email protected]>
Gerrit-Reviewer: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Marcel Kornacker <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-HasComments: Yes

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