Riza Suminto has uploaded this change for review. (
http://gerrit.cloudera.org:8080/19807
Change subject: IMPALA-12091: Control scan parallelism by its processing cost
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IMPALA-12091: Control scan parallelism by its processing cost
Before this patch, Impala still relies on MT_DOP option to decide the
degree of parallelism of the scan fragment when a query runs with
COMPUTE_PROCESSING_COST=1. This patch adds the scan node's processing
cost as another consideration to raise scan parallelism beyond MT_DOP.
Scan node cost is now adjusted to also consider the number of effective
scan ranges. Each scan range is given a weight of (0.5% *
min_processing_per_thread), which roughly means that one scan node
instance can handle at most 200 scan ranges. Query option
NUM_SCANNER_THREADS is repurposed as an upper bound on scan parallelism
if COMPUTE_PROCESSING_COST=true. If the number of scan ranges is fewer
than the maximum parallelism allowed by the scan node's processing cost,
that processing cost will be clamped down to (min_processing_per_thread
/ number of scan ranges). Lowering NUM_SCANNER_THREADS can also clamp
down the scan processing cost in a similar way.
Two new criteria are added during effective parallelism calculation in
PlanFragment.adjustToMaxParallelism():
- If a fragment has UnionNode, its parallelism is the maximum between
its input fragments and its collocated ScanNode's expected
parallelism.
- If a fragment only has a single ScanNode (and no UnionNode), its
parallelism is calculated in the same fashion as the interior fragment
but will not be lowered anymore since it will not have any child
fragment to compare with.
Admission control slots remain unchanged. This may cause a query to fail
admission if Planner selects scan parallelism that is higher than the
configured admission control slots value. Setting NUM_SCANNER_THREADS
equal to or lower than configured admission control slots value can help
lower scan parallelism and pass the admission controller.
The previous workaround to control scan parallelism by IMPALA-12029 is
now removed. This patch also disables IMPALA-10287 optimization if
COMPUTE_PROCESSING_COST=true. This is because IMPALA-10287 relies on a
fixed number of fragment instances in DistributedPlanner.java. However,
effective parallelism calculation is done much later and may change the
final number of instances of hash join fragment, rendering
DistributionMode selected by IMPALA-10287 inaccurate.
This patch is benchmarked using single_node_perf_run.py with folowing
parameters:
args="-gen_experimental_profile=true -default_query_options="
args+="mt_dop=4,compute_processing_cost=1,processing_cost_min_threads=1 "
./bin/single_node_perf_run.py --num_impalads=3 --scale=10 \
--workloads=tpcds --iterations=5 --table_formats=parquet/none/none \
--impalad_args="$args" \
--query_names=TPCDS-Q3,TPCDS-Q14-1,TPCDS-Q14-2,TPCDS-Q23-1,TPCDS-Q23-2,TPCDS-Q49,TPCDS-Q76,TPCDS-Q78,TPCDS-Q80A
\
"IMPALA-12091~1" IMPALA-12091
The benchmark result is as follow:
+-----------+-------------+-----------------------+--------+-------------+------------+------------+----------------+-------+----------------+---------+-------+
| Workload | Query | File Format | Avg(s) | Base Avg(s) |
Delta(Avg) | StdDev(%) | Base StdDev(%) | Iters | Median Diff(%) | MW Zval |
Tval |
+-----------+-------------+-----------------------+--------+-------------+------------+------------+----------------+-------+----------------+---------+-------+
| TPCDS(10) | TPCDS-Q23-1 | parquet / none / none | 4.62 | 4.54 |
+1.92% | 0.23% | 1.59% | 5 | +2.32% | 1.15 |
2.67 |
| TPCDS(10) | TPCDS-Q14-1 | parquet / none / none | 5.82 | 5.76 |
+1.08% | 5.27% | 3.89% | 5 | +2.04% | 0.00 |
0.37 |
| TPCDS(10) | TPCDS-Q23-2 | parquet / none / none | 4.65 | 4.58 |
+1.38% | 1.97% | 0.48% | 5 | +0.81% | 0.87 |
1.51 |
| TPCDS(10) | TPCDS-Q49 | parquet / none / none | 1.49 | 1.48 |
+0.46% | * 36.02% * | * 34.95% * | 5 | +1.26% | 0.58 |
0.02 |
| TPCDS(10) | TPCDS-Q14-2 | parquet / none / none | 3.76 | 3.75 |
+0.39% | 1.67% | 0.58% | 5 | -0.03% | -0.58 |
0.49 |
| TPCDS(10) | TPCDS-Q78 | parquet / none / none | 2.80 | 2.80 |
-0.04% | 1.32% | 1.33% | 5 | -0.42% | -0.29 |
-0.05 |
| TPCDS(10) | TPCDS-Q80A | parquet / none / none | 2.87 | 2.89 |
-0.51% | 1.33% | 0.40% | 5 | -0.01% | -0.29 |
-0.82 |
| TPCDS(10) | TPCDS-Q3 | parquet / none / none | 0.18 | 0.19 |
-1.29% | * 15.26% * | * 15.87% * | 5 | -0.54% | -0.87 |
-0.13 |
| TPCDS(10) | TPCDS-Q76 | parquet / none / none | 1.08 | 1.11 |
-2.98% | 0.92% | 1.70% | 5 | -3.99% | -2.02 |
-3.47 |
+-----------+-------------+-----------------------+--------+-------------+------------+------------+----------------+-------+----------------+---------+-------+
Testing:
- Pass PlannerTest.testProcessingCost
- Pass test_executor_groups.py
Change-Id: If948e45455275d9a61a6cd5d6a30a8b98a7c729a
---
M be/src/scheduling/scheduler.cc
M be/src/scheduling/scheduler.h
M fe/src/main/java/org/apache/impala/analysis/Analyzer.java
M fe/src/main/java/org/apache/impala/planner/AggregationNode.java
M fe/src/main/java/org/apache/impala/planner/DistributedPlanner.java
M fe/src/main/java/org/apache/impala/planner/EmptySetNode.java
M fe/src/main/java/org/apache/impala/planner/HdfsTableSink.java
M fe/src/main/java/org/apache/impala/planner/PlanFragment.java
M fe/src/main/java/org/apache/impala/planner/PlanNode.java
M fe/src/main/java/org/apache/impala/planner/Planner.java
M fe/src/main/java/org/apache/impala/planner/ProcessingCost.java
M fe/src/main/java/org/apache/impala/planner/ScanNode.java
M fe/src/main/java/org/apache/impala/planner/UnionNode.java
M fe/src/main/java/org/apache/impala/service/Frontend.java
M fe/src/test/resources/llama-site-3-groups.xml
M
testdata/workloads/functional-planner/queries/PlannerTest/tpcds-processing-cost.test
M tests/custom_cluster/test_executor_groups.py
17 files changed, 808 insertions(+), 774 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/07/19807/1
--
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: If948e45455275d9a61a6cd5d6a30a8b98a7c729a
Gerrit-Change-Number: 19807
Gerrit-PatchSet: 1
Gerrit-Owner: Riza Suminto <[email protected]>
