Running Spark on YARN
- Security
- Launching Spark on YARN
- Preparations
- Configuration
- Debugging your Application
- Resource Allocation and Configuration Overview
- Stage Level Scheduling Overview
- Important notes
- Kerberos
- Configuring the External Shuffle Service
- Launching your application with Apache Oozie
- Using the Spark History Server to replace the Spark Web UI
- Running multiple versions of the Spark Shuffle Service
Support for running on YARN (Hadoop NextGen) was added to Spark in version 0.6.0, and improved in subsequent releases.
Security
Security features like authentication are not enabled by default. When deploying a cluster that is open to the internet or an untrusted network, it’s important to secure access to the cluster to prevent unauthorized applications from running on the cluster. Please see Spark Security and the specific security sections in this doc before running Spark.
Launching Spark on YARN
Ensure that HADOOP_CONF_DIR
or YARN_CONF_DIR
points to the directory which contains the (client side) configuration files for the Hadoop cluster.
These configs are used to write to HDFS and connect to the YARN ResourceManager. The
configuration contained in this directory will be distributed to the YARN cluster so that all
containers used by the application use the same configuration. If the configuration references
Java system properties or environment variables not managed by YARN, they should also be set in the
Spark application’s configuration (driver, executors, and the AM when running in client mode).
There are two deploy modes that can be used to launch Spark applications on YARN. In cluster
mode, the Spark driver runs inside an application master process which is managed by YARN on the cluster, and the client can go away after initiating the application. In client
mode, the driver runs in the client process, and the application master is only used for requesting resources from YARN.
Unlike other cluster managers supported by Spark in which the master’s address is specified in the --master
parameter, in YARN mode the ResourceManager’s address is picked up from the Hadoop configuration.
Thus, the --master
parameter is yarn
.
To launch a Spark application in cluster
mode:
$ ./bin/spark-submit --class path.to.your.Class --master yarn --deploy-mode cluster [options] <app jar> [app options]
For example:
$ ./bin/spark-submit --class org.apache.spark.examples.SparkPi \
--master yarn \
--deploy-mode cluster \
--driver-memory 4g \
--executor-memory 2g \
--executor-cores 1 \
--queue thequeue \
examples/jars/spark-examples*.jar \
10
The above starts a YARN client program which starts the default Application Master. Then SparkPi will be run as a child thread of Application Master. The client will periodically poll the Application Master for status updates and display them in the console. The client will exit once your application has finished running. Refer to the Debugging your Application section below for how to see driver and executor logs.
To launch a Spark application in client
mode, do the same, but replace cluster
with client
. The following shows how you can run spark-shell
in client
mode:
$ ./bin/spark-shell --master yarn --deploy-mode client
Adding Other JARs
In cluster
mode, the driver runs on a different machine than the client, so SparkContext.addJar
won’t work out of the box with files that are local to the client. To make files on the client available to SparkContext.addJar
, include them with the --jars
option in the launch command.
$ ./bin/spark-submit --class my.main.Class \
--master yarn \
--deploy-mode cluster \
--jars my-other-jar.jar,my-other-other-jar.jar \
my-main-jar.jar \
app_arg1 app_arg2
Preparations
Running Spark on YARN requires a binary distribution of Spark which is built with YARN support.
Binary distributions can be downloaded from the downloads page of the project website.
There are two variants of Spark binary distributions you can download. One is pre-built with a certain
version of Apache Hadoop; this Spark distribution contains built-in Hadoop runtime, so we call it with-hadoop
Spark
distribution. The other one is pre-built with user-provided Hadoop; since this Spark distribution
doesn’t contain a built-in Hadoop runtime, it’s smaller, but users have to provide a Hadoop installation separately.
We call this variant no-hadoop
Spark distribution. For with-hadoop
Spark distribution, since
it contains a built-in Hadoop runtime already, by default, when a job is submitted to Hadoop Yarn cluster, to prevent jar conflict, it will not
populate Yarn’s classpath into Spark. To override this behavior, you can set spark.yarn.populateHadoopClasspath=true
.
For no-hadoop
Spark distribution, Spark will populate Yarn’s classpath by default in order to get Hadoop runtime. For with-hadoop
Spark distribution,
if your application depends on certain library that is only available in the cluster, you can try to populate the Yarn classpath by setting
the property mentioned above. If you run into jar conflict issue by doing so, you will need to turn it off and include this library
in your application jar.
To build Spark yourself, refer to Building Spark.
To make Spark runtime jars accessible from YARN side, you can specify spark.yarn.archive
or spark.yarn.jars
. For details please refer to Spark Properties. If neither spark.yarn.archive
nor spark.yarn.jars
is specified, Spark will create a zip file with all jars under $SPARK_HOME/jars
and upload it to the distributed cache.
Configuration
Most of the configs are the same for Spark on YARN as for other deployment modes. See the configuration page for more information on those. These are configs that are specific to Spark on YARN.
Debugging your Application
In YARN terminology, executors and application masters run inside “containers”. YARN has two modes for handling container logs after an application has completed. If log aggregation is turned on (with the yarn.log-aggregation-enable
config), container logs are copied to HDFS and deleted on the local machine. These logs can be viewed from anywhere on the cluster with the yarn logs
command.
yarn logs -applicationId <app ID>
will print out the contents of all log files from all containers from the given application. You can also view the container log files directly in HDFS using the HDFS shell or API. The directory where they are located can be found by looking at your YARN configs (yarn.nodemanager.remote-app-log-dir
and yarn.nodemanager.remote-app-log-dir-suffix
). The logs are also available on the Spark Web UI under the Executors Tab. You need to have both the Spark history server and the MapReduce history server running and configure yarn.log.server.url
in yarn-site.xml
properly. The log URL on the Spark history server UI will redirect you to the MapReduce history server to show the aggregated logs.
When log aggregation isn’t turned on, logs are retained locally on each machine under YARN_APP_LOGS_DIR
, which is usually configured to /tmp/logs
or $HADOOP_HOME/logs/userlogs
depending on the Hadoop version and installation. Viewing logs for a container requires going to the host that contains them and looking in this directory. Subdirectories organize log files by application ID and container ID. The logs are also available on the Spark Web UI under the Executors Tab and doesn’t require running the MapReduce history server.
To review per-container launch environment, increase yarn.nodemanager.delete.debug-delay-sec
to a
large value (e.g. 36000
), and then access the application cache through yarn.nodemanager.local-dirs
on the nodes on which containers are launched. This directory contains the launch script, JARs, and
all environment variables used for launching each container. This process is useful for debugging
classpath problems in particular. (Note that enabling this requires admin privileges on cluster
settings and a restart of all node managers. Thus, this is not applicable to hosted clusters).
To use a custom log4j configuration for the application master or executors, here are the options:
- upload a custom
log4j.properties
usingspark-submit
, by adding it to the--files
list of files to be uploaded with the application. - add
-Dlog4j.configuration=<location of configuration file>
tospark.driver.extraJavaOptions
(for the driver) orspark.executor.extraJavaOptions
(for executors). Note that if using a file, thefile:
protocol should be explicitly provided, and the file needs to exist locally on all the nodes. - update the
$SPARK_CONF_DIR/log4j.properties
file and it will be automatically uploaded along with the other configurations. Note that other 2 options has higher priority than this option if multiple options are specified.
Note that for the first option, both executors and the application master will share the same log4j configuration, which may cause issues when they run on the same node (e.g. trying to write to the same log file).
If you need a reference to the proper location to put log files in the YARN so that YARN can properly display and aggregate them, use spark.yarn.app.container.log.dir
in your log4j.properties
. For example, log4j.appender.file_appender.File=${spark.yarn.app.container.log.dir}/spark.log
. For streaming applications, configuring RollingFileAppender
and setting file location to YARN’s log directory will avoid disk overflow caused by large log files, and logs can be accessed using YARN’s log utility.
To use a custom metrics.properties for the application master and executors, update the $SPARK_CONF_DIR/metrics.properties
file. It will automatically be uploaded with other configurations, so you don’t need to specify it manually with --files
.
Spark Properties
Property Name | Default | Meaning | Since Version |
---|---|---|---|
spark.yarn.am.memory |
512m |
Amount of memory to use for the YARN Application Master in client mode, in the same format as JVM memory strings (e.g. 512m , 2g ).
In cluster mode, use spark.driver.memory instead.
Use lower-case suffixes, e.g. k , m , g , t , and p , for kibi-, mebi-, gibi-, tebi-, and pebibytes, respectively.
|
1.3.0 |
spark.yarn.am.resource.{resource-type}.amount |
(none) |
Amount of resource to use for the YARN Application Master in client mode.
In cluster mode, use spark.yarn.driver.resource.<resource-type>.amount instead.
Please note that this feature can be used only with YARN 3.0+
For reference, see YARN Resource Model documentation: https://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/ResourceModel.html
Example:
To request GPU resources from YARN, use: spark.yarn.am.resource.yarn.io/gpu.amount
|
3.0.0 |
spark.yarn.applicationType |
SPARK |
Defines more specific application types, e.g. SPARK , SPARK-SQL , SPARK-STREAMING ,
SPARK-MLLIB and SPARK-GRAPH . Please be careful not to exceed 20 characters.
|
3.1.0 |
spark.yarn.driver.resource.{resource-type}.amount |
(none) |
Amount of resource to use for the YARN Application Master in cluster mode.
Please note that this feature can be used only with YARN 3.0+
For reference, see YARN Resource Model documentation: https://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/ResourceModel.html
Example:
To request GPU resources from YARN, use: spark.yarn.driver.resource.yarn.io/gpu.amount
|
3.0.0 |
spark.yarn.executor.resource.{resource-type}.amount |
(none) |
Amount of resource to use per executor process.
Please note that this feature can be used only with YARN 3.0+
For reference, see YARN Resource Model documentation: https://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/ResourceModel.html
Example:
To request GPU resources from YARN, use: spark.yarn.executor.resource.yarn.io/gpu.amount
|
3.0.0 |
spark.yarn.resourceGpuDeviceName |
yarn.io/gpu |
Specify the mapping of the Spark resource type of gpu to the YARN resource
representing a GPU. By default YARN uses yarn.io/gpu but if YARN has been
configured with a custom resource type, this allows remapping it.
Applies when using the spark.{driver/executor}.resource.gpu.* configs.
|
3.2.1 |
spark.yarn.resourceFpgaDeviceName |
yarn.io/fpga |
Specify the mapping of the Spark resource type of fpga to the YARN resource
representing a FPGA. By default YARN uses yarn.io/fpga but if YARN has been
configured with a custom resource type, this allows remapping it.
Applies when using the spark.{driver/executor}.resource.fpga.* configs.
|
3.2.1 |
spark.yarn.am.cores |
1 |
Number of cores to use for the YARN Application Master in client mode.
In cluster mode, use spark.driver.cores instead.
|
1.3.0 |
spark.yarn.am.waitTime |
100s |
Only used in cluster mode. Time for the YARN Application Master to wait for the
SparkContext to be initialized.
|
1.3.0 |
spark.yarn.submit.file.replication |
The default HDFS replication (usually 3 ) |
HDFS replication level for the files uploaded into HDFS for the application. These include things like the Spark jar, the app jar, and any distributed cache files/archives. | 0.8.1 |
spark.yarn.stagingDir |
Current user's home directory in the filesystem | Staging directory used while submitting applications. | 2.0.0 |
spark.yarn.preserve.staging.files |
false |
Set to true to preserve the staged files (Spark jar, app jar, distributed cache files) at the end of the job rather than delete them.
|
1.1.0 |
spark.yarn.scheduler.heartbeat.interval-ms |
3000 |
The interval in ms in which the Spark application master heartbeats into the YARN ResourceManager.
The value is capped at half the value of YARN's configuration for the expiry interval, i.e.
yarn.am.liveness-monitor.expiry-interval-ms .
|
0.8.1 |
spark.yarn.scheduler.initial-allocation.interval |
200ms |
The initial interval in which the Spark application master eagerly heartbeats to the YARN ResourceManager
when there are pending container allocation requests. It should be no larger than
spark.yarn.scheduler.heartbeat.interval-ms . The allocation interval will doubled on
successive eager heartbeats if pending containers still exist, until
spark.yarn.scheduler.heartbeat.interval-ms is reached.
|
1.4.0 |
spark.yarn.max.executor.failures |
numExecutors * 2, with minimum of 3 | The maximum number of executor failures before failing the application. | 1.0.0 |
spark.yarn.historyServer.address |
(none) |
The address of the Spark history server, e.g. host.com:18080 . The address should not contain a scheme (http:// ). Defaults to not being set since the history server is an optional service. This address is given to the YARN ResourceManager when the Spark application finishes to link the application from the ResourceManager UI to the Spark history server UI.
For this property, YARN properties can be used as variables, and these are substituted by Spark at runtime. For example, if the Spark history server runs on the same node as the YARN ResourceManager, it can be set to ${hadoopconf-yarn.resourcemanager.hostname}:18080 .
|
1.0.0 |
spark.yarn.dist.archives |
(none) | Comma separated list of archives to be extracted into the working directory of each executor. | 1.0.0 |
spark.yarn.dist.files |
(none) | Comma-separated list of files to be placed in the working directory of each executor. | 1.0.0 |
spark.yarn.dist.jars |
(none) | Comma-separated list of jars to be placed in the working directory of each executor. | 2.0.0 |
spark.yarn.dist.forceDownloadSchemes |
(none) |
Comma-separated list of schemes for which resources will be downloaded to the local disk prior to being added to YARN's distributed cache. For use in cases where the YARN service does not support schemes that are supported by Spark, like http, https and ftp, or jars required to be in the local YARN client's classpath. Wildcard '*' is denoted to download resources for all the schemes. | 2.3.0 |
spark.executor.instances |
2 |
The number of executors for static allocation. With spark.dynamicAllocation.enabled , the initial set of executors will be at least this large.
|
1.0.0 |
spark.yarn.am.memoryOverhead |
AM memory * 0.10, with minimum of 384 |
Same as spark.driver.memoryOverhead , but for the YARN Application Master in client mode.
|
1.3.0 |
spark.yarn.queue |
default |
The name of the YARN queue to which the application is submitted. | 1.0.0 |
spark.yarn.jars |
(none) |
List of libraries containing Spark code to distribute to YARN containers.
By default, Spark on YARN will use Spark jars installed locally, but the Spark jars can also be
in a world-readable location on HDFS. This allows YARN to cache it on nodes so that it doesn't
need to be distributed each time an application runs. To point to jars on HDFS, for example,
set this configuration to hdfs:///some/path . Globs are allowed.
|
2.0.0 |
spark.yarn.archive |
(none) |
An archive containing needed Spark jars for distribution to the YARN cache. If set, this
configuration replaces spark.yarn.jars and the archive is used in all the
application's containers. The archive should contain jar files in its root directory.
Like with the previous option, the archive can also be hosted on HDFS to speed up file
distribution.
|
2.0.0 |
spark.yarn.appMasterEnv.[EnvironmentVariableName] |
(none) |
Add the environment variable specified by EnvironmentVariableName to the
Application Master process launched on YARN. The user can specify multiple of
these and to set multiple environment variables. In cluster mode this controls
the environment of the Spark driver and in client mode it only controls
the environment of the executor launcher.
|
1.1.0 |
spark.yarn.containerLauncherMaxThreads |
25 |
The maximum number of threads to use in the YARN Application Master for launching executor containers. | 1.2.0 |
spark.yarn.am.extraJavaOptions |
(none) |
A string of extra JVM options to pass to the YARN Application Master in client mode.
In cluster mode, use spark.driver.extraJavaOptions instead. Note that it is illegal
to set maximum heap size (-Xmx) settings with this option. Maximum heap size settings can be set
with spark.yarn.am.memory
|
1.3.0 |
spark.yarn.am.extraLibraryPath |
(none) | Set a special library path to use when launching the YARN Application Master in client mode. | 1.4.0 |
spark.yarn.populateHadoopClasspath |
For with-hadoop Spark distribution, this is set to false;
for no-hadoop distribution, this is set to true.
|
Whether to populate Hadoop classpath from yarn.application.classpath and
mapreduce.application.classpath Note that if this is set to false ,
it requires a with-Hadoop Spark distribution that bundles Hadoop runtime or
user has to provide a Hadoop installation separately.
|
2.4.6 |
spark.yarn.maxAppAttempts |
yarn.resourcemanager.am.max-attempts in YARN |
The maximum number of attempts that will be made to submit the application. It should be no larger than the global number of max attempts in the YARN configuration. | 1.3.0 |
spark.yarn.am.attemptFailuresValidityInterval |
(none) | Defines the validity interval for AM failure tracking. If the AM has been running for at least the defined interval, the AM failure count will be reset. This feature is not enabled if not configured. | 1.6.0 |
spark.yarn.am.clientModeTreatDisconnectAsFailed |
false | Treat yarn-client unclean disconnects as failures. In yarn-client mode, normally the application will always finish with a final status of SUCCESS because in some cases, it is not possible to know if the Application was terminated intentionally by the user or if there was a real error. This config changes that behavior such that if the Application Master disconnects from the driver uncleanly (ie without the proper shutdown handshake) the application will terminate with a final status of FAILED. This will allow the caller to decide if it was truly a failure. Note that if this config is set and the user just terminate the client application badly it may show a status of FAILED when it wasn't really FAILED. | 3.3.0 |
spark.yarn.am.clientModeExitOnError |
false | In yarn-client mode, when this is true, if driver got application report with final status of KILLED or FAILED, driver will stop corresponding SparkContext and exit program with code 1. Note, if this is true and called from another application, it will terminate the parent application as well. | 3.3.0 |
spark.yarn.am.tokenConfRegex |
(none) |
This config is only supported when Hadoop version is 2.9+ or 3.x (e.g., when using the Hadoop 3.x profile).
The value of this config is a regex expression used to grep a list of config entries from the job's configuration file (e.g., hdfs-site.xml)
and send to RM, which uses them when renewing delegation tokens. A typical use case of this feature is to support delegation
tokens in an environment where a YARN cluster needs to talk to multiple downstream HDFS clusters, where the YARN RM may not have configs
(e.g., dfs.nameservices, dfs.ha.namenodes.*, dfs.namenode.rpc-address.*) to connect to these clusters.
In this scenario, Spark users can specify the config value to be ^dfs.nameservices$|^dfs.namenode.rpc-address.*$|^dfs.ha.namenodes.*$ to parse
these HDFS configs from the job's local configuration files. This config is very similar to mapreduce.job.send-token-conf . Please check YARN-5910 for more details.
|
3.3.0 |
spark.yarn.executor.failuresValidityInterval |
(none) | Defines the validity interval for executor failure tracking. Executor failures which are older than the validity interval will be ignored. | 2.0.0 |
spark.yarn.submit.waitAppCompletion |
true |
In YARN cluster mode, controls whether the client waits to exit until the application completes.
If set to true , the client process will stay alive reporting the application's status.
Otherwise, the client process will exit after submission.
|
1.4.0 |
spark.yarn.am.nodeLabelExpression |
(none) | A YARN node label expression that restricts the set of nodes AM will be scheduled on. Only versions of YARN greater than or equal to 2.6 support node label expressions, so when running against earlier versions, this property will be ignored. | 1.6.0 |
spark.yarn.executor.nodeLabelExpression |
(none) | A YARN node label expression that restricts the set of nodes executors will be scheduled on. Only versions of YARN greater than or equal to 2.6 support node label expressions, so when running against earlier versions, this property will be ignored. | 1.4.0 |
spark.yarn.tags |
(none) | Comma-separated list of strings to pass through as YARN application tags appearing in YARN ApplicationReports, which can be used for filtering when querying YARN apps. | 1.5.0 |
spark.yarn.priority |
(none) | Application priority for YARN to define pending applications ordering policy, those with higher integer value have a better opportunity to be activated. Currently, YARN only supports application priority when using FIFO ordering policy. | 3.0.0 |
spark.yarn.config.gatewayPath |
(none) |
A path that is valid on the gateway host (the host where a Spark application is started) but may
differ for paths for the same resource in other nodes in the cluster. Coupled with
spark.yarn.config.replacementPath , this is used to support clusters with
heterogeneous configurations, so that Spark can correctly launch remote processes.
The replacement path normally will contain a reference to some environment variable exported by
YARN (and, thus, visible to Spark containers).
For example, if the gateway node has Hadoop libraries installed on /disk1/hadoop , and
the location of the Hadoop install is exported by YARN as the HADOOP_HOME
environment variable, setting this value to /disk1/hadoop and the replacement path to
$HADOOP_HOME will make sure that paths used to launch remote processes properly
reference the local YARN configuration.
|
1.5.0 |
spark.yarn.config.replacementPath |
(none) |
See spark.yarn.config.gatewayPath .
|
1.5.0 |
spark.yarn.rolledLog.includePattern |
(none) |
Java Regex to filter the log files which match the defined include pattern
and those log files will be aggregated in a rolling fashion.
This will be used with YARN's rolling log aggregation, to enable this feature in YARN side
yarn.nodemanager.log-aggregation.roll-monitoring-interval-seconds should be
configured in yarn-site.xml. The Spark log4j appender needs be changed to use
FileAppender or another appender that can handle the files being removed while it is running. Based
on the file name configured in the log4j configuration (like spark.log), the user should set the
regex (spark*) to include all the log files that need to be aggregated.
|
2.0.0 |
spark.yarn.rolledLog.excludePattern |
(none) | Java Regex to filter the log files which match the defined exclude pattern and those log files will not be aggregated in a rolling fashion. If the log file name matches both the include and the exclude pattern, this file will be excluded eventually. | 2.0.0 |
spark.yarn.executor.launch.excludeOnFailure.enabled |
false |
Flag to enable exclusion of nodes having YARN resource allocation problems.
The error limit for excluding can be configured by
spark.excludeOnFailure.application.maxFailedExecutorsPerNode .
|
2.4.0 |
spark.yarn.exclude.nodes |
(none) | Comma-separated list of YARN node names which are excluded from resource allocation. | 3.0.0 |
spark.yarn.metrics.namespace |
(none) | The root namespace for AM metrics reporting. If it is not set then the YARN application ID is used. | 2.4.0 |
spark.yarn.report.interval |
1s |
Interval between reports of the current Spark job status in cluster mode. | 0.9.0 |
spark.yarn.clientLaunchMonitorInterval |
1s |
Interval between requests for status the client mode AM when starting the app. | 2.3.0 |
spark.yarn.includeDriverLogsLink |
false |
In cluster mode, whether the client application report includes links to the driver container's logs. This requires polling the ResourceManager's REST API, so it places some additional load on the RM. | 3.1.0 |
spark.yarn.unmanagedAM.enabled |
false |
In client mode, whether to launch the Application Master service as part of the client using unmanaged am. | 3.0.0 |
Available patterns for SHS custom executor log URL
Pattern | Meaning |
---|---|
{{HTTP_SCHEME}} | http:// or https:// according to YARN HTTP policy. (Configured via yarn.http.policy ) |
{{NM_HOST}} | The "host" of node where container was run. |
{{NM_PORT}} | The "port" of node manager where container was run. |
{{NM_HTTP_PORT}} | The "port" of node manager's http server where container was run. |
{{NM_HTTP_ADDRESS}} | Http URI of the node on which the container is allocated. |
{{CLUSTER_ID}} | The cluster ID of Resource Manager. (Configured via yarn.resourcemanager.cluster-id ) |
{{CONTAINER_ID}} | The ID of container. |
{{USER}} | SPARK_USER on system environment. |
{{FILE_NAME}} | stdout , stderr . |
For example, suppose you would like to point log url link to Job History Server directly instead of let NodeManager http server redirects it, you can configure spark.history.custom.executor.log.url
as below:
{{HTTP_SCHEME}}<JHS_HOST>:<JHS_PORT>/jobhistory/logs/{{NM_HOST}}:{{NM_PORT}}/{{CONTAINER_ID}}/{{CONTAINER_ID}}/{{USER}}/{{FILE_NAME}}?start=-4096
NOTE: you need to replace <JHS_HOST>
and <JHS_PORT>
with actual value.
Resource Allocation and Configuration Overview
Please make sure to have read the Custom Resource Scheduling and Configuration Overview section on the configuration page. This section only talks about the YARN specific aspects of resource scheduling.
YARN needs to be configured to support any resources the user wants to use with Spark. Resource scheduling on YARN was added in YARN 3.1.0. See the YARN documentation for more information on configuring resources and properly setting up isolation. Ideally the resources are setup isolated so that an executor can only see the resources it was allocated. If you do not have isolation enabled, the user is responsible for creating a discovery script that ensures the resource is not shared between executors.
YARN supports user defined resource types but has built in types for GPU (yarn.io/gpu
) and FPGA (yarn.io/fpga
). For that reason, if you are using either of those resources, Spark can translate your request for spark resources into YARN resources and you only have to specify the spark.{driver/executor}.resource.
configs. Note, if you are using a custom resource type for GPUs or FPGAs with YARN you can change the Spark mapping using spark.yarn.resourceGpuDeviceName
and spark.yarn.resourceFpgaDeviceName
.
If you are using a resource other than FPGA or GPU, the user is responsible for specifying the configs for both YARN (spark.yarn.{driver/executor}.resource.
) and Spark (spark.{driver/executor}.resource.
).
For example, the user wants to request 2 GPUs for each executor. The user can just specify spark.executor.resource.gpu.amount=2
and Spark will handle requesting yarn.io/gpu
resource type from YARN.
If the user has a user defined YARN resource, lets call it acceleratorX
then the user must specify spark.yarn.executor.resource.acceleratorX.amount=2
and spark.executor.resource.acceleratorX.amount=2
.
YARN does not tell Spark the addresses of the resources allocated to each container. For that reason, the user must specify a discovery script that gets run by the executor on startup to discover what resources are available to that executor. You can find an example scripts in examples/src/main/scripts/getGpusResources.sh
. The script must have execute permissions set and the user should setup permissions to not allow malicious users to modify it. The script should write to STDOUT a JSON string in the format of the ResourceInformation class. This has the resource name and an array of resource addresses available to just that executor.
Stage Level Scheduling Overview
Stage level scheduling is supported on YARN when dynamic allocation is enabled. One thing to note that is YARN specific is that each ResourceProfile requires a different container priority on YARN. The mapping is simply the ResourceProfile id becomes the priority, on YARN lower numbers are higher priority. This means that profiles created earlier will have a higher priority in YARN. Normally this won’t matter as Spark finishes one stage before starting another one, the only case this might have an affect is in a job server type scenario, so its something to keep in mind.
Note there is a difference in the way custom resources are handled between the base default profile and custom ResourceProfiles. To allow for the user to request YARN containers with extra resources without Spark scheduling on them, the user can specify resources via the spark.yarn.executor.resource.
config. Those configs are only used in the base default profile though and do not get propagated into any other custom ResourceProfiles. This is because there would be no way to remove them if you wanted a stage to not have them. This results in your default profile getting custom resources defined in spark.yarn.executor.resource.
plus spark defined resources of GPU or FPGA. Spark converts GPU and FPGA resources into the YARN built in types yarn.io/gpu
) and yarn.io/fpga
, but does not know the mapping of any other resources. Any other Spark custom resources are not propagated to YARN for the default profile. So if you want Spark to schedule based off a custom resource and have it requested from YARN, you must specify it in both YARN (spark.yarn.{driver/executor}.resource.
) and Spark (spark.{driver/executor}.resource.
) configs. Leave the Spark config off if you only want YARN containers with the extra resources but Spark not to schedule using them. Now for custom ResourceProfiles, it doesn’t currently have a way to only specify YARN resources without Spark scheduling off of them. This means for custom ResourceProfiles we propagate all the resources defined in the ResourceProfile to YARN. We still convert GPU and FPGA to the YARN build in types as well. This requires that the name of any custom resources you specify match what they are defined as in YARN.
Important notes
- Whether core requests are honored in scheduling decisions depends on which scheduler is in use and how it is configured.
- In
cluster
mode, the local directories used by the Spark executors and the Spark driver will be the local directories configured for YARN (Hadoop YARN configyarn.nodemanager.local-dirs
). If the user specifiesspark.local.dir
, it will be ignored. Inclient
mode, the Spark executors will use the local directories configured for YARN while the Spark driver will use those defined inspark.local.dir
. This is because the Spark driver does not run on the YARN cluster inclient
mode, only the Spark executors do. - The
--files
and--archives
options support specifying file names with the # similar to Hadoop. For example, you can specify:--files localtest.txt#appSees.txt
and this will upload the file you have locally namedlocaltest.txt
into HDFS but this will be linked to by the nameappSees.txt
, and your application should use the name asappSees.txt
to reference it when running on YARN. - The
--jars
option allows theSparkContext.addJar
function to work if you are using it with local files and running incluster
mode. It does not need to be used if you are using it with HDFS, HTTP, HTTPS, or FTP files.
Kerberos
Standard Kerberos support in Spark is covered in the Security page.
In YARN mode, when accessing Hadoop file systems, aside from the default file system in the hadoop configuration, Spark will also automatically obtain delegation tokens for the service hosting the staging directory of the Spark application.
YARN-specific Kerberos Configuration
Property Name | Default | Meaning | Since Version |
---|---|---|---|
spark.kerberos.keytab |
(none) |
The full path to the file that contains the keytab for the principal specified above. This keytab
will be copied to the node running the YARN Application Master via the YARN Distributed Cache, and
will be used for renewing the login tickets and the delegation tokens periodically. Equivalent to
the --keytab command line argument.
(Works also with the "local" master.) |
3.0.0 |
spark.kerberos.principal |
(none) |
Principal to be used to login to KDC, while running on secure clusters. Equivalent to the
--principal command line argument.
(Works also with the "local" master.) |
3.0.0 |
spark.yarn.kerberos.relogin.period |
1m | How often to check whether the kerberos TGT should be renewed. This should be set to a value that is shorter than the TGT renewal period (or the TGT lifetime if TGT renewal is not enabled). The default value should be enough for most deployments. | 2.3.0 |
spark.yarn.kerberos.renewal.excludeHadoopFileSystems |
(none) |
A comma-separated list of Hadoop filesystems for whose hosts will be excluded from delegation
token renewal at resource scheduler. For example, spark.yarn.kerberos.renewal.excludeHadoopFileSystems=hdfs://nn1.com:8032,
hdfs://nn2.com:8032 . This is known to work under YARN for now, so YARN Resource Manager won't renew tokens for the application.
Note that as resource scheduler does not renew token, so any application running longer than the original token expiration that tries
to use that token will likely fail.
|
3.2.0 |
Troubleshooting Kerberos
Debugging Hadoop/Kerberos problems can be “difficult”. One useful technique is to
enable extra logging of Kerberos operations in Hadoop by setting the HADOOP_JAAS_DEBUG
environment variable.
export HADOOP_JAAS_DEBUG=true
The JDK classes can be configured to enable extra logging of their Kerberos and
SPNEGO/REST authentication via the system properties sun.security.krb5.debug
and sun.security.spnego.debug=true
-Dsun.security.krb5.debug=true -Dsun.security.spnego.debug=true
All these options can be enabled in the Application Master:
spark.yarn.appMasterEnv.HADOOP_JAAS_DEBUG true
spark.yarn.am.extraJavaOptions -Dsun.security.krb5.debug=true -Dsun.security.spnego.debug=true
Finally, if the log level for org.apache.spark.deploy.yarn.Client
is set to DEBUG
, the log
will include a list of all tokens obtained, and their expiry details
Configuring the External Shuffle Service
To start the Spark Shuffle Service on each NodeManager
in your YARN cluster, follow these
instructions:
- Build Spark with the YARN profile. Skip this step if you are using a pre-packaged distribution.
- Locate the
spark-<version>-yarn-shuffle.jar
. This should be under$SPARK_HOME/common/network-yarn/target/scala-<version>
if you are building Spark yourself, and underyarn
if you are using a distribution. - Add this jar to the classpath of all
NodeManager
s in your cluster. - In the
yarn-site.xml
on each node, addspark_shuffle
toyarn.nodemanager.aux-services
, then setyarn.nodemanager.aux-services.spark_shuffle.class
toorg.apache.spark.network.yarn.YarnShuffleService
. - Increase
NodeManager's
heap size by settingYARN_HEAPSIZE
(1000 by default) inetc/hadoop/yarn-env.sh
to avoid garbage collection issues during shuffle. - Restart all
NodeManager
s in your cluster.
The following extra configuration options are available when the shuffle service is running on YARN:
Property Name | Default | Meaning | |
---|---|---|---|
spark.yarn.shuffle.stopOnFailure |
false |
Whether to stop the NodeManager when there's a failure in the Spark Shuffle Service's initialization. This prevents application failures caused by running containers on NodeManagers where the Spark Shuffle Service is not running. | |
spark.yarn.shuffle.service.metrics.namespace |
sparkShuffleService |
The namespace to use when emitting shuffle service metrics into Hadoop metrics2 system of the NodeManager. | |
spark.yarn.shuffle.service.logs.namespace |
(not set) |
A namespace which will be appended to the class name when forming the logger name to use for
emitting logs from the YARN shuffle service, like
org.apache.spark.network.yarn.YarnShuffleService.logsNamespaceValue . Since some logging frameworks
may expect the logger name to look like a class name, it's generally recommended to provide a value which
would be a valid Java package or class name and not include spaces.
|
|
spark.shuffle.service.db.backend |
LEVELDB | When work-preserving restart is enabled in YARN, this is used to specify the disk-base store used in shuffle service state store, supports `LEVELDB` and `ROCKSDB` with `LEVELDB` as default value. The original data store in `LevelDB/RocksDB` will not be automatically converted to another kind of storage now. The original data store will be retained and the new type data store will be created when switching storage types. | 3.4.0 |
Please note that the instructions above assume that the default shuffle service name,
spark_shuffle
, has been used. It is possible to use any name here, but the values used in the
YARN NodeManager configurations must match the value of spark.shuffle.service.name
in the
Spark application.
The shuffle service will, by default, take all of its configurations from the Hadoop Configuration
used by the NodeManager (e.g. yarn-site.xml
). However, it is also possible to configure the
shuffle service independently using a file named spark-shuffle-site.xml
which should be placed
onto the classpath of the shuffle service (which is, by default, shared with the classpath of the
NodeManager). The shuffle service will treat this as a standard Hadoop Configuration resource and
overlay it on top of the NodeManager’s configuration.
Launching your application with Apache Oozie
Apache Oozie can launch Spark applications as part of a workflow. In a secure cluster, the launched application will need the relevant tokens to access the cluster’s services. If Spark is launched with a keytab, this is automatic. However, if Spark is to be launched without a keytab, the responsibility for setting up security must be handed over to Oozie.
The details of configuring Oozie for secure clusters and obtaining credentials for a job can be found on the Oozie web site in the “Authentication” section of the specific release’s documentation.
For Spark applications, the Oozie workflow must be set up for Oozie to request all tokens which the application needs, including:
- The YARN resource manager.
- The local Hadoop filesystem.
- Any remote Hadoop filesystems used as a source or destination of I/O.
- Hive —if used.
- HBase —if used.
- The YARN timeline server, if the application interacts with this.
To avoid Spark attempting —and then failing— to obtain Hive, HBase and remote HDFS tokens, the Spark configuration must be set to disable token collection for the services.
The Spark configuration must include the lines:
spark.security.credentials.hive.enabled false
spark.security.credentials.hbase.enabled false
The configuration option spark.kerberos.access.hadoopFileSystems
must be unset.
Using the Spark History Server to replace the Spark Web UI
It is possible to use the Spark History Server application page as the tracking URL for running applications when the application UI is disabled. This may be desirable on secure clusters, or to reduce the memory usage of the Spark driver. To set up tracking through the Spark History Server, do the following:
- On the application side, set
spark.yarn.historyServer.allowTracking=true
in Spark’s configuration. This will tell Spark to use the history server’s URL as the tracking URL if the application’s UI is disabled. - On the Spark History Server, add
org.apache.spark.deploy.yarn.YarnProxyRedirectFilter
to the list of filters in thespark.ui.filters
configuration.
Be aware that the history server information may not be up-to-date with the application’s state.
Running multiple versions of the Spark Shuffle Service
Please note that this section only applies when running on YARN versions >= 2.9.0.
In some cases it may be desirable to run multiple instances of the Spark Shuffle Service which are
using different versions of Spark. This can be helpful, for example, when running a YARN cluster
with a mixed workload of applications running multiple Spark versions, since a given version of
the shuffle service is not always compatible with other versions of Spark. YARN versions since 2.9.0
support the ability to run shuffle services within an isolated classloader
(see YARN-4577), meaning multiple Spark versions
can coexist within a single NodeManager. The
yarn.nodemanager.aux-services.<service-name>.classpath
and, starting from YARN 2.10.2/3.1.1/3.2.0,
yarn.nodemanager.aux-services.<service-name>.remote-classpath
options can be used to configure
this. Note that YARN 3.3.0/3.3.1 have an issue which requires setting
yarn.nodemanager.aux-services.<service-name>.system-classes
as a workaround. See
YARN-11053 for details. In addition to setting
up separate classpaths, it’s necessary to ensure the two versions advertise to different ports.
This can be achieved using the spark-shuffle-site.xml
file described above. For example, you may
have configuration like:
yarn.nodemanager.aux-services = spark_shuffle_x,spark_shuffle_y
yarn.nodemanager.aux-services.spark_shuffle_x.classpath = /path/to/spark-x-path/fat.jar:/path/to/spark-x-config
yarn.nodemanager.aux-services.spark_shuffle_y.classpath = /path/to/spark-y-path/fat.jar:/path/to/spark-y-config
Or
yarn.nodemanager.aux-services = spark_shuffle_x,spark_shuffle_y
yarn.nodemanager.aux-services.spark_shuffle_x.classpath = /path/to/spark-x-path/*:/path/to/spark-x-config
yarn.nodemanager.aux-services.spark_shuffle_y.classpath = /path/to/spark-y-path/*:/path/to/spark-y-config
The two spark-*-config
directories each contain one file, spark-shuffle-site.xml
. These are XML
files in the Hadoop Configuration format
which each contain a few configurations to adjust the port number and metrics name prefix used:
<configuration>
<property>
<name>spark.shuffle.service.port</name>
<value>7001</value>
</property>
<property>
<name>spark.yarn.shuffle.service.metrics.namespace</name>
<value>sparkShuffleServiceX</value>
</property>
</configuration>
The values should both be different for the two different services.
Then, in the configuration of the Spark applications, one should be configured with:
spark.shuffle.service.name = spark_shuffle_x
spark.shuffle.service.port = 7001
and one should be configured with:
spark.shuffle.service.name = spark_shuffle_y
spark.shuffle.service.port = <other value>