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Message-Id: <201611172252.uAHMq2Qp028985@ip-10-146-233-104.ec2.internal>
Date: Thu, 17 Nov 2016 22:52:01 +0000
From: "Tim Armstrong (Code Review)" <gerrit@cloudera.org>
To: Michael Ho <kwho@cloudera.com>, impala-cr@cloudera.com,
        reviews@impala.incubator.apache.org
CC: Marcel Kornacker <marcel@cloudera.com>
Reply-To: tarmstrong@cloudera.com
Subject: =?UTF-8?Q?=5BImpala-ASF-CR=5D_IMPALA-4397=2CIMPALA-3259=3A_reduce_codegen_time_and_memory=0A?=
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References: <gerrit.1478296024000.Id10015b49da182cb181a653ac8464b4a18b71091@gerrit.cloudera.org>
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archived-at: Thu, 17 Nov 2016 22:52:46 -0000

Hello Michael Ho,

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

    http://gerrit.cloudera.org:8080/4956

to look at the new patch set (#8).

Change subject: IMPALA-4397,IMPALA-3259: reduce codegen time and memory
......................................................................

IMPALA-4397,IMPALA-3259: reduce codegen time and memory

A handful of fixes to codegen memory usage:
* Delete the IR module when we're done with it (it can be fairly large)
* Track the compiled code size (typically not that large, but it can add
  up if there are many fragments).
* Estimate optimisation memory requirements and track it in the memory
  tracker. This is very crude but much better than not tracking it.

A handful of fixes to improve codegen time/cost, particularly targeted
at compute stats workloads:
* Avoid over-inlining when there are many aggregate functions,
  conjuncts, etc by adding "NoInline" attributes.
* Bail of out text scanner codegen for wide tables.
* Don't codegen non-grouping merge aggregations. They will only process
  one row per Impala daemon, so codegen is not worth it.
* Make the Hll algorithm more efficient by specialising the hash function
  based on decimal width.

Limitations:
* This doesn't tackle over-inlining of large expr trees, but a similar
  approach will be used there in a follow-on patch.

Perf:
Compute stats on functional_parquet.widetable_1000_cols goes from 1min+
of codegen to < 1s codegen on my machine. Local perf runs of tpc-h
and targeted perf showed no regressions and some moderate improvements
(1-2%).

Also did an experiment to understand the perf consequences of disabling
inlining. I manually set CODEGEN_INLINE_EXPRS_THRESHOLD to 0, and ran:

  drop stats tpch_20_parquet.lineitem
  compute stats tpch_20_parquet.lineitem;

There was no difference in time spent in the agg node: 30.7s with
inlining, 30.5s without.

Change-Id: Id10015b49da182cb181a653ac8464b4a18b71091
---
M be/src/benchmarks/hash-benchmark.cc
M be/src/codegen/llvm-codegen-test.cc
M be/src/codegen/llvm-codegen.cc
M be/src/codegen/llvm-codegen.h
M be/src/codegen/mcjit-mem-mgr.h
M be/src/exec/aggregation-node.cc
M be/src/exec/exchange-node.cc
M be/src/exec/exec-node.cc
M be/src/exec/exec-node.h
M be/src/exec/hash-join-node.cc
M be/src/exec/hash-table.cc
M be/src/exec/hdfs-scan-node-base.cc
M be/src/exec/hdfs-scanner.cc
M be/src/exec/hdfs-scanner.h
M be/src/exec/partitioned-aggregation-node.cc
M be/src/exec/partitioned-hash-join-node.cc
M be/src/exec/sort-node.cc
M be/src/exec/topn-node.cc
M be/src/exprs/aggregate-functions-ir.cc
M be/src/exprs/anyval-util.h
M be/src/exprs/expr-codegen-test.cc
M be/src/exprs/expr.h
M be/src/runtime/lib-cache.cc
M be/src/runtime/runtime-state.cc
M common/thrift/PlanNodes.thrift
M fe/src/main/java/org/apache/impala/planner/DistributedPlanner.java
M fe/src/main/java/org/apache/impala/planner/PlanNode.java
M testdata/workloads/functional-query/queries/QueryTest/compute-stats.test
M tests/query_test/test_aggregation.py
29 files changed, 1,467 insertions(+), 165 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/56/4956/8
-- 
To view, visit http://gerrit.cloudera.org:8080/4956
To unsubscribe, visit http://gerrit.cloudera.org:8080/settings

Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Id10015b49da182cb181a653ac8464b4a18b71091
Gerrit-PatchSet: 8
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Marcel Kornacker <marcel@cloudera.com>
Gerrit-Reviewer: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>