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[SPARK-14602][YARN] Use SparkConf to propagate the list of cached files.

Marcelo Vanzin authored 9 years ago

This change avoids using the environment to pass this information, since
with many jars it's easy to hit limits on certain OSes. Instead, it encodes
the information into the Spark configuration propagated to the AM.

The first problem that needed to be solved is a chicken & egg issue: the
config file is distributed using the cache, and it needs to contain information
about the files that are being distributed. To solve that, the code now treats
the config archive especially, and uses slightly different code to distribute
it, so that only its cache path needs to be saved to the config file.

The second problem is that the extra information would show up in the Web UI,
which made the environment tab even more noisy than it already is when lots
of jars are listed. This is solved by two changes: the list of cached files
is now read only once in the AM, and propagated down to the ExecutorRunnable
code (which actually sends the list to the NMs when starting containers). The
second change is to unset those config entries after the list is read, so that
the SparkContext never sees them.

Tested with both client and cluster mode by running "run-example SparkPi". This
uploads a whole lot of files when run from a build dir (instead of a distribution,
where the list is cleaned up), and I verified that the configs do not show
up in the UI.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #12487 from vanzin/SPARK-14602.

f47dbf27

f47dbf27 9 years ago

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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.