Hello Alexey Serbin, Kudu Jenkins, Adar Dembo,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/15064
to look at the new patch set (#4).
Change subject: schema: use dense_hash_map instead of std::unordered_map
......................................................................
schema: use dense_hash_map instead of std::unordered_map
In a time series benchmark I'm working on, the client spent 12% of its
CPU in Schema::FindColumn. In particular, most of the CPU went to the
bucket calculation in std::unordered_map, which required a 'divq'
instruction that can take hundreds of cycles.
This switches Schema to use a dense_hash_map instead which performs
better. After this change, the percent of CPU used by my benchmark
worker thread in Schema::FindColumn dropped from ~12% to ~1.5% which
resulted in a few percent overall throughput increase.
This also made the fancy allocator which tried to count memory usage
unnecessary, since dense_hash_map is a simple enough data structure that
we can directly compute the memory usage. Now we can also simplify the
constructors since we no longer need to pass an allocator instance.
Change-Id: I8e8f80229b2dcfad05e204a6f6e50ce7dc3f4c73
---
M src/kudu/client/client-test.cc
M src/kudu/common/schema.cc
M src/kudu/common/schema.h
M src/kudu/common/wire_protocol.cc
M thirdparty/download-thirdparty.sh
A
thirdparty/patches/sparsehash-0002-Add-workaround-for-dense_hashtable-move-constructor-.patch
6 files changed, 87 insertions(+), 85 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/64/15064/4
--
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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I8e8f80229b2dcfad05e204a6f6e50ce7dc3f4c73
Gerrit-Change-Number: 15064
Gerrit-PatchSet: 4
Gerrit-Owner: Todd Lipcon <t...@apache.org>
Gerrit-Reviewer: Adar Dembo <a...@cloudera.com>
Gerrit-Reviewer: Alexey Serbin <aser...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Todd Lipcon <t...@apache.org>
