Apache Spark - A unified analytics engine for large-scale data processing
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Tejas Patil 94439997d5 [SPARK-21595] Separate thresholds for buffering and spilling in ExternalAppendOnlyUnsafeRowArray
## What changes were proposed in this pull request?

[SPARK-21595](https://issues.apache.org/jira/browse/SPARK-21595) reported that there is excessive spilling to disk due to default spill threshold for `ExternalAppendOnlyUnsafeRowArray` being quite small for WINDOW operator. Old behaviour of WINDOW operator (pre https://github.com/apache/spark/pull/16909) would hold data in an array for first 4096 records post which it would switch to `UnsafeExternalSorter` and start spilling to disk after reaching `spark.shuffle.spill.numElementsForceSpillThreshold` (or earlier if there was paucity of memory due to excessive consumers).

Currently the (switch from in-memory to `UnsafeExternalSorter`) and (`UnsafeExternalSorter` spilling to disk) for `ExternalAppendOnlyUnsafeRowArray` is controlled by a single threshold. This PR aims to separate that to have more granular control.

## How was this patch tested?

Added unit tests

Author: Tejas Patil <tejasp@fb.com>

Closes #18843 from tejasapatil/SPARK-21595.
2017-08-11 22:01:00 +02:00
.github [SPARK-18073][DOCS][WIP] Migrate wiki to spark.apache.org web site 2016-11-23 11:25:47 +00:00
assembly [SPARK-7481][BUILD] Add spark-hadoop-cloud module to pull in object store access. 2017-05-07 10:15:31 +01:00
bin [SPARK-19810][BUILD][CORE] Remove support for Scala 2.10 2017-07-13 17:06:24 +08:00
build [SPARK-19810][BUILD][CORE] Remove support for Scala 2.10 2017-07-13 17:06:24 +08:00
common [SPARK-21671][CORE] Move kvstore to "util" sub-package, add private annotation. 2017-08-08 14:33:27 -07:00
conf [SPARK-21305][ML][MLLIB] Add options to disable multi-threading of native BLAS 2017-07-12 11:02:04 +01:00
core [SPARK-21675][WEBUI] Add a navigation bar at the bottom of the Details for Stage Page 2017-08-11 14:57:06 +01:00
data [SPARK-16421][EXAMPLES][ML] Improve ML Example Outputs 2016-08-05 20:57:46 +01:00
dev [SPARK-21276][CORE] Update lz4-java to the latest (v1.4.0) 2017-08-09 17:31:52 +02:00
docs [SPARK-21519][SQL] Add an option to the JDBC data source to initialize the target DB environment 2017-08-11 12:03:37 -07:00
examples [SPARK-21415] Triage scapegoat warnings, part 1 2017-07-18 08:47:17 +01:00
external [SPARK-21276][CORE] Update lz4-java to the latest (v1.4.0) 2017-08-09 17:31:52 +02:00
graphx [SPARK-21491][GRAPHX] Enhance GraphX performance: breakOut instead of .toMap 2017-07-25 21:43:39 +01:00
hadoop-cloud [SPARK-7481][BUILD] Add spark-hadoop-cloud module to pull in object store access. 2017-05-07 10:15:31 +01:00
launcher [SPARK-21665][CORE] Need to close resources after use 2017-08-09 15:18:38 +02:00
licenses [MINOR][BUILD] Add modernizr MIT license; specify "2014 and onwards" in license copyright 2016-06-04 21:41:27 +01:00
mllib [SPARK-21638][ML] Fix RF/GBT Warning message error 2017-08-10 21:38:03 +01:00
mllib-local [SPARK-19810][BUILD][CORE] Remove support for Scala 2.10 2017-07-13 17:06:24 +08:00
project [SPARK-21276][CORE] Update lz4-java to the latest (v1.4.0) 2017-08-09 17:31:52 +02:00
python [SPARK-14932][SQL] Allow DataFrame.replace() to replace values with None 2017-08-09 17:42:21 -07:00
R [SPARK-21622][ML][SPARKR] Support offset in SparkR GLM 2017-08-06 15:14:12 -07:00
repl [SPARK-21339][CORE] spark-shell --packages option does not add jars to classpath on windows 2017-08-01 13:39:23 -07:00
resource-managers [SPARK-13041][MESOS] Adds sandbox uri to spark dispatcher ui 2017-08-07 10:32:19 +01:00
sbin [SPARK-21278][PYSPARK] Upgrade to Py4J 0.10.6 2017-07-05 16:33:23 -07:00
sql [SPARK-21595] Separate thresholds for buffering and spilling in ExternalAppendOnlyUnsafeRowArray 2017-08-11 22:01:00 +02:00
streaming [SPARK-21357][DSTREAMS] FileInputDStream not remove out of date RDD 2017-07-29 13:27:39 +01:00
tools [SPARK-20453] Bump master branch version to 2.3.0-SNAPSHOT 2017-04-24 21:48:04 -07:00
.gitattributes [SPARK-3870] EOL character enforcement 2014-10-31 12:39:52 -07:00
.gitignore [SPARK-21485][SQL][DOCS] Spark SQL documentation generation for built-in functions 2017-07-26 09:38:51 -07:00
.travis.yml [SPARK-19801][BUILD] Remove JDK7 from Travis CI 2017-03-03 12:00:54 +01:00
appveyor.yml [MINOR][R] Add knitr and rmarkdown packages/improve output for version info in AppVeyor tests 2017-06-18 08:43:47 +01:00
CONTRIBUTING.md [SPARK-18073][DOCS][WIP] Migrate wiki to spark.apache.org web site 2016-11-23 11:25:47 +00:00
LICENSE [SPARK-21278][PYSPARK] Upgrade to Py4J 0.10.6 2017-07-05 16:33:23 -07:00
NOTICE [SPARK-18262][BUILD][SQL] JSON.org license is now CatX 2016-11-10 10:20:03 -08:00
pom.xml [SPARK-21276][CORE] Update lz4-java to the latest (v1.4.0) 2017-08-09 17:31:52 +02:00
README.md [MINOR][DOCS] Replace non-breaking space to normal spaces that breaks rendering markdown 2017-04-03 10:09:11 +01:00
scalastyle-config.xml [SPARK-13747][CORE] Add ThreadUtils.awaitReady and disallow Await.ready 2017-05-17 17:21:46 -07:00

Apache Spark

Spark is a fast and general cluster computing system for Big Data. It provides high-level APIs in Scala, Java, Python, and R, and an optimized engine that supports general computation graphs for data analysis. It also supports a rich set of higher-level tools including Spark SQL for SQL and DataFrames, MLlib for machine learning, GraphX for graph processing, and Spark Streaming for stream processing.

http://spark.apache.org/

Online Documentation

You can find the latest Spark documentation, including a programming guide, on the project web page. This README file only contains basic setup instructions.

Building Spark

Spark is built using Apache Maven. To build Spark and its example programs, run:

build/mvn -DskipTests clean package

(You do not need to do this if you downloaded a pre-built package.)

You can build Spark using more than one thread by using the -T option with Maven, see "Parallel builds in Maven 3". More detailed documentation is available from the project site, at "Building Spark".

For general development tips, including info on developing Spark using an IDE, see "Useful Developer Tools".

Interactive Scala Shell

The easiest way to start using Spark is through the Scala shell:

./bin/spark-shell

Try the following command, which should return 1000:

scala> sc.parallelize(1 to 1000).count()

Interactive Python Shell

Alternatively, if you prefer Python, you can use the Python shell:

./bin/pyspark

And run the following command, which should also return 1000:

>>> sc.parallelize(range(1000)).count()

Example Programs

Spark also comes with several sample programs in the examples directory. To run one of them, use ./bin/run-example <class> [params]. For example:

./bin/run-example SparkPi

will run the Pi example locally.

You can set the MASTER environment variable when running examples to submit examples to a cluster. This can be a mesos:// or spark:// URL, "yarn" to run on YARN, and "local" to run locally with one thread, or "local[N]" to run locally with N threads. You can also use an abbreviated class name if the class is in the examples package. For instance:

MASTER=spark://host:7077 ./bin/run-example SparkPi

Many of the example programs print usage help if no params are given.

Running Tests

Testing first requires building Spark. Once Spark is built, tests can be run using:

./dev/run-tests

Please see the guidance on how to run tests for a module, or individual tests.

A Note About Hadoop Versions

Spark uses the Hadoop core library to talk to HDFS and other Hadoop-supported storage systems. Because the protocols have changed in different versions of Hadoop, you must build Spark against the same version that your cluster runs.

Please refer to the build documentation at "Specifying the Hadoop Version" for detailed guidance on building for a particular distribution of Hadoop, including building for particular Hive and Hive Thriftserver distributions.

Configuration

Please refer to the Configuration Guide in the online documentation for an overview on how to configure Spark.

Contributing

Please review the Contribution to Spark guide for information on how to get started contributing to the project.