Spark’s default build strategy is to assemble a jar including all of its dependencies. This can be cumbersome when doing iterative development. When developing locally, it is possible to create an assembly jar including all of Spark’s dependencies and then re-package only Spark itself when making changes.
$ build/sbt clean package $ ./bin/spark-shell $ export SPARK_PREPEND_CLASSES=true $ ./bin/spark-shell # Now it's using compiled classes # ... do some local development ... # $ build/sbt compile # ... do some local development ... # $ build/sbt compile $ unset SPARK_PREPEND_CLASSES $ ./bin/spark-shell # You can also use ~ to let sbt do incremental builds on file changes without running a new sbt session every time $ build/sbt ~compile
Zinc is a long-running server version of SBT’s incremental
compiler. When run locally as a background process, it speeds up builds of Scala-based projects
like Spark. Developers who regularly recompile Spark with Maven will be the most interested in
Zinc. The project site gives instructions for building and running
zinc; OS X users can
install it using
brew install zinc.
If using the
zinc will automatically be downloaded and leveraged for all
builds. This process will auto-start after the first time
build/mvn is called and bind to port
3030 unless the
ZINC_PORT environment variable is set. The
zinc process can subsequently be
shut down at any time by running
build/zinc-<version>/bin/zinc -shutdown and will automatically
build/mvn is called.
For instance, you can build the Spark Core module using:
$ # sbt $ build/sbt > project core > package $ # or you can build the spark-core module with sbt directly using: $ build/sbt core/package $ # Maven $ build/mvn package -DskipTests -pl core
When developing locally, it’s often convenient to run a single test or a few tests, rather than running the entire test suite.
The fastest way to run individual tests is to use the
sbt console. It’s fastest to keep a
sbt console open, and use it to re-run tests as necessary. For example, to run all of the tests in a particular project, e.g.,
$ build/sbt > project core > test
You can run a single test suite using the
testOnly command. For example, to run the DAGSchedulerSuite:
> testOnly org.apache.spark.scheduler.DAGSchedulerSuite
testOnly command accepts wildcards; e.g., you can also run the
> testOnly *DAGSchedulerSuite
Or you could run all of the tests in the scheduler package:
> testOnly org.apache.spark.scheduler.*
If you’d like to run just a single test in the
DAGSchedulerSuite, e.g., a test that includes “SPARK-12345” in the name, you run the following command in the sbt console:
> testOnly *DAGSchedulerSuite -- -z "SPARK-12345"
If you’d prefer, you can run all of these commands on the command line (but this will be slower than running tests using an open cosole). To do this, you need to surround
testOnly and the following arguments in quotes:
$ build/sbt "core/testOnly *DAGSchedulerSuite -- -z SPARK-12345"
For more about how to run individual tests with sbt, see the sbt documentation.
With Maven, you can use the
-DwildcardSuites flag to run individual Scala tests:
build/mvn -Dtest=none -DwildcardSuites=org.apache.spark.scheduler.DAGSchedulerSuite test
-Dtest=none to avoid running the Java tests. For more information about the ScalaTest Maven Plugin, refer to the ScalaTest documentation.
To run individual Java tests, you can use the
build/mvn test -DwildcardSuites=none -Dtest=org.apache.spark.streaming.JavaAPISuite test
If the following error occurs when running ScalaTest
An internal error occurred during: "Launching XYZSuite.scala". java.lang.NullPointerException
It is due to an incorrect Scala library in the classpath. To fix it:
Build Path | Configure Build Path
Add Library | Scala Library
scala-library-2.10.4.jar - lib_managed\jars
In the event of “Could not find resource path for Web UI: org/apache/spark/ui/static”, it’s due to a classpath issue (some classes were probably not compiled). To fix this, it sufficient to run a test from the command line:
build/sbt "test-only org.apache.spark.rdd.SortingSuite"
When running tests for a pull request on Jenkins, you can add special phrases to the title of your pull request to change testing behavior. This includes:
[test-maven]- signals to test the pull request using maven
[test-hadoop2.7]- signals to test using Spark’s Hadoop 2.7 profile
To ensure binary compatibility, Spark uses MiMa.
When working on an issue, it’s always a good idea to check that your changes do not introduce binary incompatibilities before opening a pull request.
You can do so by running the following command:
A binary incompatibility reported by MiMa might look like the following:
[error] method this(org.apache.spark.sql.Dataset)Unit in class org.apache.spark.SomeClass does not have a correspondent in current version [error] filter with: ProblemFilters.exclude[DirectMissingMethodProblem]("org.apache.spark.SomeClass.this")
If you open a pull request containing binary incompatibilities anyway, Jenkins will remind you by failing the test build with the following message:
Test build #xx has finished for PR yy at commit ffffff. This patch fails MiMa tests. This patch merges cleanly. This patch adds no public classes.
If you believe that your binary incompatibilies are justified or that MiMa reported false positives (e.g. the reported binary incompatibilities are about a non-user facing API), you can filter them out by adding an exclusion in project/MimaExcludes.scala containing what was suggested by the MiMa report and a comment containing the JIRA number of the issue you’re working on as well as its title.
For the problem described above, we might add the following:
Otherwise, you will have to resolve those incompatibilies before opening or updating your pull request. Usually, the problems reported by MiMa are self-explanatory and revolve around missing members (methods or fields) that you will have to add back in order to maintain binary compatibility.
Git provides a mechanism for fetching remote pull requests into your own local repository. This is useful when reviewing code or testing patches locally. If you haven’t yet cloned the Spark Git repository, use the following command:
$ git clone https://github.com/apache/spark.git $ cd spark
To enable this feature you’ll need to configure the git remote repository to fetch pull request
data. Do this by modifying the
.git/config file inside of your Spark directory. The remote may
not be named “origin” if you’ve named it something else:
[remote "origin"] url = email@example.com:apache/spark.git fetch = +refs/heads/*:refs/remotes/origin/* fetch = +refs/pull/*/head:refs/remotes/origin/pr/* # Add this line
Once you’ve done this you can fetch remote pull requests
# Fetch remote pull requests $ git fetch origin # Checkout a remote pull request $ git checkout origin/pr/112 # Create a local branch from a remote pull request $ git checkout origin/pr/112 -b new-branch
$ # sbt $ build/sbt dependency-tree $ # Maven $ build/mvn -DskipTests install $ build/mvn dependency:tree
You can use a IntelliJ Imports Organizer from Aaron Davidson to help you organize the imports in your code. It can be configured to match the import ordering from the style guide.
While many of the Spark developers use SBT or Maven on the command line, the most common IDE we
use is IntelliJ IDEA. You can get the community edition for free (Apache committers can get
free IntelliJ Ultimate Edition licenses) and install the JetBrains Scala plugin from
Preferences > Plugins.
To create a Spark project for IntelliJ:
File -> Import Project, locate the spark source directory, and select “Maven Project”.
-P[profile name]above may be enabled on the Profiles screen in the Import wizard. For example, if developing for Hadoop 2.7 with YARN support, enable profiles
hadoop-2.7. These selections can be changed later by accessing the “Maven Projects” tool window from the View menu, and expanding the Profiles section.
/Users/irashid/github/spark/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodeGenerator.scala Error:(147, 9) value q is not a member of StringContext Note: implicit class Evaluate2 is not applicable here because it comes after the application point and it lacks an explicit result type q""" ^
Eclipse can be used to develop and test Spark. The following configuration is known to work:
The easiest way is to download the Scala IDE bundle from the Scala IDE download page. It comes pre-installed with ScalaTest. Alternatively, use the Scala IDE update site or Eclipse Marketplace.
SBT can create Eclipse
.classpath files. To create these files for each Spark sub
project, use this command:
To import a specific project, e.g. spark-core, select
File | Import | Existing Projects into
Workspace. Do not select “Copy projects into workspace”.
If you want to develop on Scala 2.10 you need to configure a Scala installation for the
exact Scala version that’s used to compile Spark.
Since Scala IDE bundles the latest versions (2.10.5 and 2.11.8 at this point), you need to add one
Eclipse Preferences -> Scala -> Installations by pointing to the
lib/ directory of your
Scala 2.10.5 distribution. Once this is done, select all Spark projects and right-click,
Scala -> Set Scala Installation and point to the 2.10.5 installation.
This should clear all errors about invalid cross-compiled libraries. A clean build should succeed now.
ScalaTest can execute unit tests by right clicking a source file and selecting
Run As | Scala Test.
If Java memory errors occur, it might be necessary to increase the settings in
in the Eclipse install directory. Increase the following setting as needed:
Packages are built regularly off of Spark’s master branch and release branches. These provide Spark developers access to the bleeding-edge of Spark master or the most recent fixes not yet incorporated into a maintenance release. These should only be used by Spark developers, as they may have bugs and have not undergone the same level of testing as releases. Spark nightly packages are available at:
Spark also publishes SNAPSHOT releases of its Maven artifacts for both master and maintenance branches on a nightly basis. To link to a SNAPSHOT you need to add the ASF snapshot repository to your build. Note that SNAPSHOT artifacts are ephemeral and may change or be removed. To use these you must add the ASF snapshot repository at <a href=”https://repository.apache.org/snapshots/.
groupId: org.apache.spark artifactId: spark-core_2.10 version: 1.5.0-SNAPSHOT
Here are instructions on profiling Spark applications using YourKit Java Profiler.
/rootin our case):
~/spark/conf/spark-env.shand adding the lines
SPARK_DAEMON_JAVA_OPTS+=" -agentpath:/root/YourKit-JavaProfiler-2017.02/bin/linux-x86-64/libyjpagent.so=sampling" export SPARK_DAEMON_JAVA_OPTS SPARK_EXECUTOR_OPTS+=" -agentpath:/root/YourKit-JavaProfiler-2017.02/bin/linux-x86-64/libyjpagent.so=sampling" export SPARK_EXECUTOR_OPTS
10001-10010. To connect the YourKit desktop application to the remote profiler agents, you’ll have to open these ports in the cluster’s EC2 security groups. To do this, sign into the AWS Management Console. Go to the EC2 section and select
Security Groupsfrom the
Network & Securitysection on the left side of the page. Find the security groups corresponding to your cluster; if you launched a cluster named
test_cluster, then you will want to modify the settings for the
test_cluster-mastersecurity groups. For each group, select it from the list, click the
Inboundtab, and create a new
Custom TCP Ruleopening the port range
10001-10010. Finally, click
Apply Rule Changes. Make sure to do this for both security groups. Note: by default,
spark-ec2re-uses security groups: if you stop this cluster and launch another cluster with the same name, your security group settings will be re-used.
Please see the full YourKit documentation for the full list of profiler agent startup options.
When running Spark tests through SBT, add
javaOptions in Test += "-agentpath:/path/to/yjp"
SparkBuild.scala to launch the tests with the YourKit profiler agent enabled.
The platform-specific paths to the profiler agents are listed in the YourKit documentation.