Apache Spark - A unified analytics engine for large-scale data processing
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Liang-Chi Hsieh 7920296bf8 [SPARK-15430][SQL] Fix potential ConcurrentModificationException for ListAccumulator
## What changes were proposed in this pull request?

In `ListAccumulator` we create an unmodifiable view for underlying list. However, it doesn't prevent the underlying to be modified further. So as we access the unmodifiable list, the underlying list can be modified in the same time. It could cause `java.util.ConcurrentModificationException`. We can observe such exception in recent tests.

To fix it, we can copy a list of the underlying list and then create the unmodifiable view of this list instead.

## How was this patch tested?
The exception might be difficult to test. Existing tests should be passed.

Author: Liang-Chi Hsieh <simonh@tw.ibm.com>

Closes #13211 from viirya/fix-concurrentmodify.
2016-05-22 08:08:46 -05:00
.github [MINOR][MAINTENANCE] Fix typo for the pull request template. 2016-02-24 00:45:31 -08:00
assembly [SPARK-14925][BUILD] Re-introduce 'unused' dependency so that published POMs are flattened 2016-04-26 15:14:17 -07:00
bin [SPARK-15061][PYSPARK] Upgrade to Py4J 0.10.1 2016-05-13 08:59:18 +01:00
build [SPARK-14867][BUILD] Remove --force option in build/mvn 2016-04-27 20:56:23 +01:00
common [SPARK-15386][CORE] Master doesn't compile against Java 1.7 / Process.isAlive 2016-05-18 14:22:21 -07:00
conf [SPARK-14134][CORE] Change the package name used for shading classes. 2016-04-06 19:33:51 -07:00
core [SPARK-15430][SQL] Fix potential ConcurrentModificationException for ListAccumulator 2016-05-22 08:08:46 -05:00
data [SPARK-15150][EXAMPLE][DOC] Update LDA examples 2016-05-11 12:49:41 +02:00
dev [SPARK-15424][SPARK-15437][SPARK-14807][SQL] Revert Create a hivecontext-compatibility module 2016-05-20 22:01:55 -07:00
docs [SPARK-15396][SQL][DOC] It can't connect hive metastore database 2016-05-21 23:12:27 -07:00
examples [SPARK-15396][SQL][DOC] It can't connect hive metastore database 2016-05-21 23:12:27 -07:00
external [SPARK-15290][BUILD] Move annotations, like @Since / @DeveloperApi, into spark-tags 2016-05-17 09:55:53 +01:00
graphx [SPARK-15290][BUILD] Move annotations, like @Since / @DeveloperApi, into spark-tags 2016-05-17 09:55:53 +01:00
launcher [SPARK-15360][SPARK-SUBMIT] Should print spark-submit usage when no arguments is specified 2016-05-20 10:28:24 -07:00
licenses [SPARK-14050][ML] Add multiple languages support and additional methods for Stop Words Remover 2016-05-06 13:58:12 -07:00
mllib [SPARK-15339][ML] ML 2.0 QA: Scala APIs and code audit for regression 2016-05-19 23:35:20 -07:00
mllib-local [SPARK-15411][ML] Add @since to ml.stat.MultivariateOnlineSummarizer.scala 2016-05-19 13:10:51 -07:00
project [SPARK-15424][SPARK-15437][SPARK-14807][SQL] Revert Create a hivecontext-compatibility module 2016-05-20 22:01:55 -07:00
python [SPARK-15456][PYSPARK] Fixed PySpark shell context initialization when HiveConf not present 2016-05-20 16:41:57 -07:00
R [SPARK-14463][SQL] Document the semantics for read.text 2016-05-18 19:16:28 -07:00
repl [SPARK-15290][BUILD] Move annotations, like @Since / @DeveloperApi, into spark-tags 2016-05-17 09:55:53 +01:00
sbin [SPARK-15203][DEPLOY] The spark daemon shell script error, daemon process start successfully but script output fail message 2016-05-20 08:17:19 -05:00
sql [SPARK-15428][SQL] Disable multiple streaming aggregations 2016-05-22 02:08:18 -07:00
streaming [SPARK-15290][BUILD] Move annotations, like @Since / @DeveloperApi, into spark-tags 2016-05-17 09:55:53 +01:00
tools [MINOR][DOCS] Use multi-line JavaDoc comments in Scala code. 2016-04-02 17:50:40 -07:00
yarn [SPARK-15273] YarnSparkHadoopUtil#getOutOfMemoryErrorArgument should respect OnOutOfMemoryError parameter given by user 2016-05-20 18:13:18 -05:00
.gitattributes [SPARK-3870] EOL character enforcement 2014-10-31 12:39:52 -07:00
.gitignore [MINOR][BUILD] Adds spark-warehouse/ to .gitignore 2016-05-05 14:33:14 -07:00
.travis.yml [SPARK-15207][BUILD] Use Travis CI for Java Linter and JDK7/8 compilation test 2016-05-10 21:04:22 +01:00
CONTRIBUTING.md [SPARK-6889] [DOCS] CONTRIBUTING.md updates to accompany contribution doc updates 2015-04-21 22:34:31 -07:00
LICENSE [SPARK-15061][PYSPARK] Upgrade to Py4J 0.10.1 2016-05-13 08:59:18 +01:00
NOTICE [SPARK-12154] Upgrade to Jersey 2 2016-05-05 10:51:03 +01:00
pom.xml [SPARK-15424][SPARK-15437][SPARK-14807][SQL] Revert Create a hivecontext-compatibility module 2016-05-20 22:01:55 -07:00
README.md Add links howto to setup IDEs for developing spark 2015-12-04 14:43:16 +00:00
scalastyle-config.xml [SPARK-6429] Implement hashCode and equals together 2016-04-22 12:24:12 +01:00

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 and project wiki. 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 developing Spark using an IDE, see Eclipse and IntelliJ.

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.