Tim Armstrong has posted comments on this change.

Change subject: IMPALA-3611: track unused Disk IO buffer memory
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Patch Set 1:

(5 comments)

http://gerrit.cloudera.org:8080/#/c/3246/1/be/src/runtime/disk-io-mgr-test.cc
File be/src/runtime/disk-io-mgr-test.cc:

Line 932: TEST_F(DiskIoMgrTest, Buffers) {
Had to make more more fixes in this test - the version I pushed was missing 
some fixed I made locally but didn't squash into the patchset correctly.


http://gerrit.cloudera.org:8080/#/c/3246/1/be/src/runtime/disk-io-mgr.cc
File be/src/runtime/disk-io-mgr.cc:

PS1, Line 239: if (mem_tracker_ != NULL) mem_tracker_->Consume(buffer_len_);
> Not your change but this should really be TryConsume() in the long run too.
Agreed, but I think we need to look at the whole lifecycle of the buffers to 
work out the right technique to throttle the scans when memory is scarce.


PS1, Line 700: Consume(buffer_size)
> Do you think it makes sense to convert this to TryConsume() in the long run
I feel like this will probably change once we rework the scanner memory 
management anyway, so it may not be worth doing the plumbing at this point to 
thread through a TryConsume() failure. It looks tricky.

I cleaned up the memory transfer to avoid doing the transfer in 
GetBufferDesc(). This works out cleaner.


PS1, Line 764: SetMemTracker(
> This is a bit of a misnomer. Do you think it makes sense to call it Transfe
Done


PS1, Line 829: process_limit_exceeded = buffer_mem_tracker_->AnyLimitExceeded();
> I wonder if this check should be moved to ReturnFreeBuffer() ? Also, this i
Changed to any_io_mgr_limit_exceeded. In practice the only limit that applies 
to the io mgr now is the process limit, but the naming seems more correct in 
content.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I8777cf76f04d34a46f53d53005412e0f1d63b5b7
Gerrit-PatchSet: 1
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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