Apache Spark - A unified analytics engine for large-scale data processing
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Josh Rosen d50f8df929 [SPARK-30413][SQL] Avoid WrappedArray roundtrip in GenericArrayData constructor, plus related optimization in ParquetMapConverter
### What changes were proposed in this pull request?

This PR implements a tiny performance optimization for a `GenericArrayData` constructor, avoiding an unnecessary roundtrip through `WrappedArray` when the provided value is already an array of objects.

It also fixes a related performance problem in `ParquetRowConverter`.

### Why are the changes needed?

`GenericArrayData` has a `this(seqOrArray: Any)` constructor, which was originally added in #13138 for use in `RowEncoder` (where we may not know concrete types until runtime) but is also called (perhaps unintentionally) in a few other code paths.

In this constructor's existing implementation, a call to `new WrappedArray(Array[Object](""))` is dispatched to the `this(seqOrArray: Any)` constructor, where we then call `this(array.toSeq)`: this wraps the provided array into a `WrappedArray`, which is subsequently unwrapped in a `this(seq.toArray)` call. For an interactive example, see https://scastie.scala-lang.org/7jOHydbNTaGSU677FWA8nA

This PR changes the `this(seqOrArray: Any)` constructor so that it calls the primary `this(array: Array[Any])` constructor, allowing us to save a `.toSeq.toArray` call; this comes at the cost of one additional `case` in the `match` statement (but I believe this has a negligible performance impact relative to the other savings).

As code cleanup, I also reverted the JVM 1.7 workaround from #14271.

I also fixed a related performance problem in `ParquetRowConverter`: previously, this code called `ArrayBasedMapData.apply` which, in turn, called the `this(Any)` constructor for `GenericArrayData`: this PR's micro-benchmarks show that this is _significantly_ slower than calling the `this(Array[Any])` constructor (and I also observed time spent here during other Parquet scan benchmarking work). To fix this performance problem, I replaced the call to the  `ArrayBasedMapData.apply` method with direct calls to the `ArrayBasedMapData` and `GenericArrayData` constructors.

### Does this PR introduce any user-facing change?

No.

### How was this patch tested?

I tested this by running code in a debugger and by running microbenchmarks (which I've added to a new `GenericArrayDataBenchmark` in this PR):

- With JDK8 benchmarks: this PR's changes more than double the performance of calls to the `this(Any)` constructor. Even after improvements, however, calls to the `this(Array[Any])` constructor are still ~60x faster than calls to `this(Any)` when passing a non-primitive array (thereby motivating this patch's other change in `ParquetRowConverter`).
- With JDK11 benchmarks: the changes more-or-less completely eliminate the performance penalty associated with the `this(Any)` constructor.

Closes #27088 from JoshRosen/joshrosen/GenericArrayData-optimization.

Authored-by: Josh Rosen <rosenville@gmail.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
2020-01-19 19:12:19 -08:00
.github [SPARK-30572][BUILD] Add a fallback Maven repository 2020-01-19 17:42:34 -08:00
assembly [SPARK-30489][BUILD] Make build delete pyspark.zip file properly 2020-01-10 16:59:51 -08:00
bin [SPARK-28525][DEPLOY] Allow Launcher to be applied Java options 2019-07-30 12:45:32 -07:00
build [SPARK-30121][BUILD] Fix memory usage in sbt build script 2019-12-05 11:50:55 -06:00
common [SPARK-30551][SQL] Disable comparison for interval type 2020-01-19 15:27:51 +08:00
conf [SPARK-29032][CORE] Add PrometheusServlet to monitor Master/Worker/Driver 2019-09-13 21:31:21 +00:00
core [SPARK-30566][BUILD] Iterator doesn't refer outer identifier named "iterator" properly in Scala 2.13 2020-01-20 10:11:41 +09:00
data [SPARK-22666][ML][SQL] Spark datasource for image format 2018-09-05 11:59:00 -07:00
dev [SPARK-30486][BUILD] Bump lz4-java version to 1.7.1 2020-01-19 19:05:30 -08:00
docs [SPARK-30282][DOCS][FOLLOWUP] Update SQL migration guide for SHOW TBLPROPERTIES 2020-01-19 14:44:12 -08:00
examples [SPARK-30423][SQL] Deprecate UserDefinedAggregateFunction 2020-01-14 22:07:13 +08:00
external [SPARK-30495][SS] Consider spark.security.credentials.kafka.enabled and cluster configuration when checking latest delegation token 2020-01-15 11:46:34 -08:00
graphx [INFRA] Reverts commit 56dcd79 and c216ef1 2019-12-16 19:57:44 -07:00
hadoop-cloud [INFRA] Reverts commit 56dcd79 and c216ef1 2019-12-16 19:57:44 -07:00
launcher [INFRA] Reverts commit 56dcd79 and c216ef1 2019-12-16 19:57:44 -07:00
licenses [SPARK-27557][DOC] Add copy button to Python API docs for easier copying of code-blocks 2019-05-01 11:26:18 -05:00
licenses-binary [SPARK-29308][BUILD] Update deps in dev/deps/spark-deps-hadoop-3.2 for hadoop-3.2 2019-10-13 12:53:12 -05:00
mllib [MINOR][ML] Change DecisionTreeClassifier to FMClassifier in OneVsRest setWeightCol test 2020-01-17 10:04:41 +08:00
mllib-local [SPARK-30329][ML] add iterator/foreach methods for Vectors 2019-12-31 15:52:17 +08:00
project [SPARK-30544][BUILD] Upgrade the version of Genjavadoc to 0.15 2020-01-18 00:15:49 -08:00
python [SPARK-30539][PYTHON][SQL] Add DataFrame.tail in PySpark 2020-01-18 00:18:12 -08:00
R [SPARK-30188][SQL] Resolve the failed unit tests when enable AQE 2020-01-13 22:55:19 +08:00
repl [INFRA] Reverts commit 56dcd79 and c216ef1 2019-12-16 19:57:44 -07:00
resource-managers [SPARK-30371][K8S] Add spark.kubernetes.driver.master conf 2020-01-19 14:14:45 -08:00
sbin [SPARK-28164] Fix usage description of start-slave.sh 2019-06-26 12:42:33 -05:00
sql [SPARK-30413][SQL] Avoid WrappedArray roundtrip in GenericArrayData constructor, plus related optimization in ParquetMapConverter 2020-01-19 19:12:19 -08:00
streaming [INFRA] Reverts commit 56dcd79 and c216ef1 2019-12-16 19:57:44 -07:00
tools [INFRA] Reverts commit 56dcd79 and c216ef1 2019-12-16 19:57:44 -07:00
.gitattributes [SPARK-3870] EOL character enforcement 2014-10-31 12:39:52 -07:00
.gitignore [SPARK-30084][DOCS] Document how to trigger Jekyll build on Python API doc changes 2019-12-04 17:31:23 -06:00
appveyor.yml [SPARK-29991][INFRA] Support Hive 1.2 and Hive 2.3 (default) in PR builder 2019-11-30 12:48:15 +09:00
CONTRIBUTING.md [MINOR][DOCS] Tighten up some key links to the project and download pages to use HTTPS 2019-05-21 10:56:42 -07:00
LICENSE [SPARK-29674][CORE] Update dropwizard metrics to 4.1.x for JDK 9+ 2019-11-03 15:13:06 -08:00
LICENSE-binary Revert [SPARK-27300][GRAPH] Add Spark Graph modules and dependencies 2019-12-17 09:06:23 -08:00
NOTICE [SPARK-29674][CORE] Update dropwizard metrics to 4.1.x for JDK 9+ 2019-11-03 15:13:06 -08:00
NOTICE-binary [SPARK-29674][CORE] Update dropwizard metrics to 4.1.x for JDK 9+ 2019-11-03 15:13:06 -08:00
pom.xml [SPARK-30486][BUILD] Bump lz4-java version to 1.7.1 2020-01-19 19:05:30 -08:00
README.md [MINOR][DOCS] Remove note about -T for parallel build 2020-01-18 11:48:43 -08:00
scalastyle-config.xml [SPARK-30030][INFRA] Use RegexChecker instead of TokenChecker to check org.apache.commons.lang. 2019-11-25 12:03:15 -08:00

Apache Spark

Spark is a unified analytics engine for large-scale data processing. 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 Structured Streaming for stream processing.

https://spark.apache.org/

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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.)

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 1,000,000,000:

scala> spark.range(1000 * 1000 * 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 1,000,000,000:

>>> spark.range(1000 * 1000 * 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.

There is also a Kubernetes integration test, see resource-managers/kubernetes/integration-tests/README.md

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 and Enabling YARN" 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.