Tim Armstrong has posted comments on this change.

Change subject: IMPALA-3611: track unused Disk IO buffer memory
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Patch Set 4:

(4 comments)

http://gerrit.cloudera.org:8080/#/c/3246/4/be/src/runtime/disk-io-mgr.cc
File be/src/runtime/disk-io-mgr.cc:

PS4, Line 210: Clear(
> Will Reset() be a better name ? This seems to match Reset() below.
Done


PS4, Line 219:   mem_tracker_ = NULL;
> nit: Can this be at line 213 so we initialize the fields in the same order 
Done here and below.

I think it's better to initialize it, so done.


Line 781:     if (!FLAGS_disable_mem_pools && free_buffers_[idx].size() < 
FLAGS_max_free_io_buffers) {
> Long line.
Fixed long line.

Using TryConsume() here could result in a deadlock since if it hits the process 
memory limit, it will call GcIoBuffers(), which attempts to grab 
free_buffers_lock_. Added a comment.


PS4, Line 856: bool any_io_mgr_limit_exceeded = 
free_buffer_mem_tracker_->AnyLimitExceeded();
> Will it be more obvious if we move this line into ReturnFreeBuffer() instea
See the comment above for why we can't do that. Note that this 
AnyLimitExceeded() check will call GcIoBuffers() if the process memory limit is 
exceeded. That isn't the best way to handle it, but fixing it is a bigger task.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I8777cf76f04d34a46f53d53005412e0f1d63b5b7
Gerrit-PatchSet: 4
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Tim Armstrong <[email protected]>
Gerrit-Reviewer: Michael Ho
Gerrit-Reviewer: Michael Ho <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-HasComments: Yes

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