Hello Matthew Jacobs,

I'd like you to reexamine a change.  Please visit

    http://gerrit.cloudera.org:8080/6626

to look at the new patch set (#9).

Change subject: IMPALA-5220: memory maintenance cleanup
......................................................................

IMPALA-5220: memory maintenance cleanup

Remove logic that tries to release pages from TcMalloc's page heap:
TCMalloc's behaviour changed so that it automatically does this with
"aggressive decommit" and committed spans can't accumulate in the page
heap.

Also increase the memory maintenance interval - 1s is too aggressive and
can free memory that will be imminently reused by a running query, e.g.
particularly buffer pool buffers.

Testing:
Tried to reproduce IMPALA-2800 in a couple of ways:
* Ran a big aggregation locally and cancelled it
* Looked at memz/ of some live clusters (production and stress test).
In all cases "Bytes in page heap freelist" was 0.

This confirms that IMPALA-2800 was already solved, probably
by the gperftools 2.5 upgrade, where aggressive decommit
would mean that memory is released to the system in
free() instead of the ReleaseFreeMemory() callst.

I was able to confirm that the ReleaseFreeMemory() calls were unnecessary
to avoid retaining memory by running a couple of stress tests
locally with this patch and checking that "Bytes in page
heap freelist" was 0 after the change and that memory consumption
was generally sensible.

Change-Id: I0f822b294ab253d6f2828fc52f353aecaaf9b701
---
M be/src/common/init.cc
M be/src/runtime/exec-env.cc
M be/src/runtime/mem-tracker.cc
M be/src/runtime/mem-tracker.h
M be/src/util/memory-metrics.h
5 files changed, 25 insertions(+), 89 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/26/6626/9
-- 
To view, visit http://gerrit.cloudera.org:8080/6626
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I0f822b294ab253d6f2828fc52f353aecaaf9b701
Gerrit-PatchSet: 9
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <tarmstr...@cloudera.com>
Gerrit-Reviewer: Bharath Vissapragada <bhara...@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhe...@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <m...@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com>
Gerrit-Reviewer: anujphadke <apha...@cloudera.com>

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