Tim Armstrong has posted comments on this change.

Change subject: IMPALA-3202: DiskIoMgr improvements for new buffer pool
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Patch Set 1:

(8 comments)

http://gerrit.cloudera.org:8080/#/c/4631/1/be/src/exec/hdfs-scan-node-base.h
File be/src/exec/hdfs-scan-node-base.h:

PS1, Line 193: BufferOpts
> const& ?
Done


http://gerrit.cloudera.org:8080/#/c/4631/1/be/src/runtime/disk-io-mgr.cc
File be/src/runtime/disk-io-mgr.cc:

PS1, Line 642: without the client providing a "
             :           "buffer"
> is this going to make sense to a user?
Probably not. The old message wasn't actionable either by a user (beyond 
reporting the bug). Reworded to make it clear that it's an internal error.


Line 708:   DCHECK_LE(buffer_size, max_buffer_size_);
> how do we ensure this is true? is it the check in DiskIoMgr::Read() that wi
DiskIoMgr::ReadRange() checks if there's a client buffer before calling 
TryAllocateNextBufferForRange().


http://gerrit.cloudera.org:8080/#/c/4631/1/be/src/runtime/disk-io-mgr.h
File be/src/runtime/disk-io-mgr.h:

PS1, Line 147: these buffers are returned to the caller wrapped
             : /// in BufferDescriptors.
> took a few seconds to parse and understand. how about:
Yes that's better...


Line 150: /// another read. In error cases, the IoMgr will recycle the buffers 
more promptly but
> is this relevant for all cases, or only cases (a) and (b)?
Tried to clarify. Also removed the last sentence since I think it was confusing 
and not really useful to the reader.


PS1, Line 392: bool
> maybe make all of these members 'const' since they are "options" that don't
Done


PS1, Line 422: BufferOpts
> const BufferOpts& ?
Done


Line 506:     int64_t client_buffer_len_;
> maybe move this right before cached_buffer_ since it's related in the sense
Switched it to a tagged union. We don't really have much precedent in the 
codebase for this pattern so I invented some conventions that made sense to me.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I913fbb8ae6c242f1585992eb2a622509344dccec
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <[email protected]>
Gerrit-Reviewer: Dan Hecht <[email protected]>
Gerrit-Reviewer: Michael Ho
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-HasComments: Yes

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