Submitting Applications
The spark-submit
script in Spark’s bin
directory is used to launch applications on a cluster.
It can use all of Spark’s supported cluster managers
through a uniform interface so you don’t have to configure your application especially for each one.
Bundling Your Application’s Dependencies
If your code depends on other projects, you will need to package them alongside
your application in order to distribute the code to a Spark cluster. To do this,
create an assembly jar (or “uber” jar) containing your code and its dependencies. Both
sbt and
Maven
have assembly plugins. When creating assembly jars, list Spark and Hadoop
as provided
dependencies; these need not be bundled since they are provided by
the cluster manager at runtime. Once you have an assembled jar you can call the bin/spark-submit
script as shown here while passing your jar.
For Python, you can use the --py-files
argument of spark-submit
to add .py
, .zip
or .egg
files to be distributed with your application. If you depend on multiple Python files we recommend
packaging them into a .zip
or .egg
.
Launching Applications with spark-submit
Once a user application is bundled, it can be launched using the bin/spark-submit
script.
This script takes care of setting up the classpath with Spark and its
dependencies, and can support different cluster managers and deploy modes that Spark supports:
Some of the commonly used options are:
--class
: The entry point for your application (e.g.org.apache.spark.examples.SparkPi
)--master
: The master URL for the cluster (e.g.spark://23.195.26.187:7077
)--deploy-mode
: Whether to deploy your driver on the worker nodes (cluster
) or locally as an external client (client
) (default:client
) †--conf
: Arbitrary Spark configuration property in key=value format. For values that contain spaces wrap “key=value” in quotes (as shown).application-jar
: Path to a bundled jar including your application and all dependencies. The URL must be globally visible inside of your cluster, for instance, anhdfs://
path or afile://
path that is present on all nodes.application-arguments
: Arguments passed to the main method of your main class, if any
† A common deployment strategy is to submit your application from a gateway machine
that is
physically co-located with your worker machines (e.g. Master node in a standalone EC2 cluster).
In this setup, client
mode is appropriate. In client
mode, the driver is launched directly
within the spark-submit
process which acts as a client to the cluster. The input and
output of the application is attached to the console. Thus, this mode is especially suitable
for applications that involve the REPL (e.g. Spark shell).
Alternatively, if your application is submitted from a machine far from the worker machines (e.g.
locally on your laptop), it is common to use cluster
mode to minimize network latency between
the drivers and the executors. Currently, the standalone mode does not support cluster mode for Python
applications.
For Python applications, simply pass a .py
file in the place of <application-jar>
instead of a JAR,
and add Python .zip
, .egg
or .py
files to the search path with --py-files
.
There are a few options available that are specific to the
cluster manager that is being used.
For example, with a Spark standalone cluster with cluster
deploy mode,
you can also specify --supervise
to make sure that the driver is automatically restarted if it
fails with a non-zero exit code. To enumerate all such options available to spark-submit
,
run it with --help
. Here are a few examples of common options:
Master URLs
The master URL passed to Spark can be in one of the following formats:
Master URL | Meaning |
---|---|
local | Run Spark locally with one worker thread (i.e. no parallelism at all). |
local[K] | Run Spark locally with K worker threads (ideally, set this to the number of cores on your machine). |
local[K,F] | Run Spark locally with K worker threads and F maxFailures (see spark.task.maxFailures for an explanation of this variable) |
local[*] | Run Spark locally with as many worker threads as logical cores on your machine. |
local[*,F] | Run Spark locally with as many worker threads as logical cores on your machine and F maxFailures. |
spark://HOST:PORT | Connect to the given Spark standalone cluster master. The port must be whichever one your master is configured to use, which is 7077 by default. |
spark://HOST1:PORT1,HOST2:PORT2 | Connect to the given Spark standalone cluster with standby masters with Zookeeper. The list must have all the master hosts in the high availability cluster set up with Zookeeper. The port must be whichever each master is configured to use, which is 7077 by default. |
mesos://HOST:PORT | Connect to the given Mesos cluster.
The port must be whichever one your is configured to use, which is 5050 by default.
Or, for a Mesos cluster using ZooKeeper, use mesos://zk://... .
To submit with --deploy-mode cluster , the HOST:PORT should be configured to connect to the MesosClusterDispatcher.
|
yarn | Connect to a YARN cluster in
client or cluster mode depending on the value of --deploy-mode .
The cluster location will be found based on the HADOOP_CONF_DIR or YARN_CONF_DIR variable.
|
k8s://HOST:PORT | Connect to a Kubernetes cluster in
cluster mode. Client mode is currently unsupported and will be supported in future releases.
The HOST and PORT refer to the [Kubernetes API Server](https://kubernetes.io/docs/reference/generated/kube-apiserver/).
It connects using TLS by default. In order to force it to use an unsecured connection, you can use
k8s://http://HOST:PORT .
|
Loading Configuration from a File
The spark-submit
script can load default Spark configuration values from a
properties file and pass them on to your application. By default it will read options
from conf/spark-defaults.conf
in the Spark directory. For more detail, see the section on
loading default configurations.
Loading default Spark configurations this way can obviate the need for certain flags to
spark-submit
. For instance, if the spark.master
property is set, you can safely omit the
--master
flag from spark-submit
. In general, configuration values explicitly set on a
SparkConf
take the highest precedence, then flags passed to spark-submit
, then values in the
defaults file.
If you are ever unclear where configuration options are coming from, you can print out fine-grained
debugging information by running spark-submit
with the --verbose
option.
Advanced Dependency Management
When using spark-submit
, the application jar along with any jars included with the --jars
option
will be automatically transferred to the cluster. URLs supplied after --jars
must be separated by commas. That list is included in the driver and executor classpaths. Directory expansion does not work with --jars
.
Spark uses the following URL scheme to allow different strategies for disseminating jars:
- file: - Absolute paths and
file:/
URIs are served by the driver’s HTTP file server, and every executor pulls the file from the driver HTTP server. - hdfs:, http:, https:, ftp: - these pull down files and JARs from the URI as expected
- local: - a URI starting with local:/ is expected to exist as a local file on each worker node. This means that no network IO will be incurred, and works well for large files/JARs that are pushed to each worker, or shared via NFS, GlusterFS, etc.
Note that JARs and files are copied to the working directory for each SparkContext on the executor nodes.
This can use up a significant amount of space over time and will need to be cleaned up. With YARN, cleanup
is handled automatically, and with Spark standalone, automatic cleanup can be configured with the
spark.worker.cleanup.appDataTtl
property.
Users may also include any other dependencies by supplying a comma-delimited list of Maven coordinates
with --packages
. All transitive dependencies will be handled when using this command. Additional
repositories (or resolvers in SBT) can be added in a comma-delimited fashion with the flag --repositories
.
(Note that credentials for password-protected repositories can be supplied in some cases in the repository URI,
such as in https://user:password@host/...
. Be careful when supplying credentials this way.)
These commands can be used with pyspark
, spark-shell
, and spark-submit
to include Spark Packages.
For Python, the equivalent --py-files
option can be used to distribute .egg
, .zip
and .py
libraries
to executors.
More Information
Once you have deployed your application, the cluster mode overview describes the components involved in distributed execution, and how to monitor and debug applications.