IMPALA-9146: Add a configurable limit for the size of broadcast input.

Impala's DistributedPlanner may sometimes accidentally choose broadcast
distribution for inputs that are larger than the destination executor's
total memory. This could potentially happen if the cluster membership is
not accurately known and the planner's cost computation of the
broadcastCost vs partitionCost happens to favor the broadcast
distribution. This causes spilling and severely affects performance.
Although the DistributedPlanner does a mem_limit check before picking
broadcast, the mem_limit is not an accurate reflection since it is
assigned during admission control.

As a safety here we introduce an explicit configurable limit:
broadcast_bytes_limit for the size of the broadcast input and set it
to default of 32GB. The default is chosen based on analysis of existing
benchmark queries and representative workloads such that in vast
majority of the cases the parameter value does not need to be changed.
If the estimated input size on the build side is greater than this
threshold, the DistributedPlanner will fall back to a partition
distribution. Setting this parameter to 0 causes it to be ignored.

Testing:
 - Ran all regression tests on Jenkins successfully
 - Added a few unit testis in PlannerTest that (a) set the
broadcast_bytes_limit to a small value and checks whether the
distributed plan does hash partitioning on the build side instead
of broadcast, (b) pass a broadcast hint to override the config
setting, (c) verify the standard case where broadcast threshold
is larger than the build input size.

Change-Id: Ibe5639ca38acb72e0194aa80bc6ebb6cafb2acd9
Reviewed-on: http://gerrit.cloudera.org:8080/14690
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
10 files changed
tree: 00a78f580371235b665c0c6c86c9727f080c6344
  1. .clang-format
  2. .clang-tidy
  3. .gitattributes
  4. .gitignore
  5. CMakeLists.txt
  6. EXPORT_CONTROL.md
  7. LICENSE.txt
  8. LOGS.md
  9. NOTICE.txt
  10. README.md
  11. be/
  12. bin/
  13. buildall.sh
  14. cmake_modules/
  15. common/
  16. docker/
  17. docs/
  18. ext-data-source/
  19. fe/
  20. impala-parent/
  21. infra/
  22. lib/
  23. query-event-hook-api/
  24. security/
  25. setup.cfg
  26. shaded-deps/
  27. shell/
  28. ssh_keys/
  29. testdata/
  30. tests/
  31. www/
README.md

Welcome to Impala

Lightning-fast, distributed SQL queries for petabytes of data stored in Apache Hadoop clusters.

Impala is a modern, massively-distributed, massively-parallel, C++ query engine that lets you analyze, transform and combine data from a variety of data sources:

  • Best of breed performance and scalability.
  • Support for data stored in HDFS, Apache HBase and Amazon S3.
  • Wide analytic SQL support, including window functions and subqueries.
  • On-the-fly code generation using LLVM to generate CPU-efficient code tailored specifically to each individual query.
  • Support for the most commonly-used Hadoop file formats, including the Apache Parquet project.
  • Apache-licensed, 100% open source.

More about Impala

To learn more about Impala as a business user, or to try Impala live or in a VM, please visit the Impala homepage.

If you are interested in contributing to Impala as a developer, or learning more about Impala's internals and architecture, visit the Impala wiki.

Supported Platforms

Impala only supports Linux at the moment.

Export Control Notice

This distribution uses cryptographic software and may be subject to export controls. Please refer to EXPORT_CONTROL.md for more information.

Build Instructions

See bin/bootstrap_build.sh.

Detailed Build Notes

Impala can be built with pre-built components or components downloaded from S3. The components needed to build Impala are Apache Hadoop, Hive, HBase, and Sentry. If you need to manually override the locations or versions of these components, you can do so through the environment variables and scripts listed below.

Scripts and directories
LocationPurpose
bin/impala-config.shThis script must be sourced to setup all environment variables properly to allow other scripts to work
bin/impala-config-local.shA script can be created in this location to set local overrides for any environment variables
bin/impala-config-branch.shA version of the above that can be checked into a branch for convenience.
bin/bootstrap_build.shA helper script to bootstrap some of the build requirements.
bin/bootstrap_development.shA helper script to bootstrap a developer environment. Please read it before using.
be/build/Impala build output goes here.
be/generated-sources/Thrift and other generated source will be found here.
Build Related Variables
Environment variableDefault valueDescription
IMPALA_HOMETop level Impala directory
IMPALA_TOOLCHAIN“${IMPALA_HOME}/toolchain”Native toolchain directory (for compilers, libraries, etc.)
SKIP_TOOLCHAIN_BOOTSTRAP“false”Skips downloading the toolchain any python dependencies if “true”
CDH_BUILD_NUMBERIdentifier to indicate the CDH build number
CDH_COMPONENTS_HOME“${IMPALA_HOME}/toolchain/cdh_components-${CDH_BUILD_NUMBER}”Location of the CDH components within the toolchain.
CDH_MAJOR_VERSION“5”Identifier used to uniqueify paths for potentially incompatible component builds.
IMPALA_CONFIG_SOURCED“1”Set by ${IMPALA_HOME}/bin/impala-config.sh (internal use)
JAVA_HOME“/usr/lib/jvm/${JAVA_VERSION}”Used to locate Java
JAVA_VERSION“java-7-oracle-amd64”Can override to set a local Java version.
JAVA“${JAVA_HOME}/bin/java”Java binary location.
CLASSPATHSee bin/set-classpath.sh for details.
PYTHONPATHWill be changed to include: “${IMPALA_HOME}/shell/gen-py” “${IMPALA_HOME}/testdata” “${THRIFT_HOME}/python/lib/python2.7/site-packages” “${HIVE_HOME}/lib/py” “${IMPALA_HOME}/shell/ext-py/prettytable-0.7.1/dist/prettytable-0.7.1” "${IMPALA_HOME}/shell/ext-py/sasl-0.1.1/dist/sasl-0.1.1-py2.7-linux-x "${IMPALA_HOME}/shell/ext-py/sqlparse-0.1.19/dist/sqlparse-0.1.19-py2
Source Directories for Impala
Environment variableDefault valueDescription
IMPALA_BE_DIR“${IMPALA_HOME}/be”Backend directory. Build output is also stored here.
IMPALA_FE_DIR“${IMPALA_HOME}/fe”Frontend directory
IMPALA_COMMON_DIR“${IMPALA_HOME}/common”Common code (thrift, function registry)
Various Compilation Settings
Environment variableDefault valueDescription
IMPALA_BUILD_THREADS“8” or set to number of processors by default.Used for make -j and distcc -j settings.
IMPALA_MAKE_FLAGS""Any extra settings to pass to make. Also used when copying udfs / udas into HDFS.
USE_SYSTEM_GCC“0”If set to any other value, directs cmake to not set GCC_ROOT, CMAKE_C_COMPILER, CMAKE_CXX_COMPILER, as well as setting TOOLCHAIN_LINK_FLAGS
IMPALA_CXX_COMPILER“default”Used by cmake (cmake_modules/toolchain and clang_toolchain.cmake) to select gcc / clang
USE_GOLD_LINKER“true”Directs backend cmake to use gold.
IS_OSX“false”(Experimental) currently only used to disable Kudu.
Dependencies
Environment variableDefault valueDescription
HADOOP_HOME“${CDH_COMPONENTS_HOME}/hadoop-${IMPALA_HADOOP_VERSION}/”Used to locate Hadoop
HADOOP_INCLUDE_DIR“${HADOOP_HOME}/include”For ‘hdfs.h’
HADOOP_LIB_DIR“${HADOOP_HOME}/lib”For ‘libhdfs.a’ or ‘libhdfs.so’
HIVE_HOME“${CDH_COMPONENTS_HOME}/{hive-${IMPALA_HIVE_VERSION}/”
HBASE_HOME“${CDH_COMPONENTS_HOME}/hbase-${IMPALA_HBASE_VERSION}/”
SENTRY_HOME“${CDH_COMPONENTS_HOME}/sentry-${IMPALA_SENTRY_VERSION}/”Used to setup test data
THRIFT_HOME“${IMPALA_TOOLCHAIN}/thrift-${IMPALA_THRIFT_VERSION}”