4.5. Manage the Application Lifecycle

Once started, applications can be stopped, restarted, destroyed, and flexed as follows:

stop <name> [--force] [--wait time] [--message text]

Stops the application instance. The running application is stopped. Its settings are retained in HDFS.

The --wait argument can specify a time in seconds to wait for the application instance to be stopped.

The --force flag causes YARN asked directly to terminate the application instance. The --message argument supplies an optional text message to be used in the request: this will appear in the application's diagnostics in the YARN RM UI.

If an unknown (or already stopped) application instance is named, no error is returned.

Example:

/usr/hdp/current/slider-client/bin/./slider stop app1

start <name> [--wait milliseconds] [--out <filename>] Start a stopped application instance, recreating it from its previously saved state.

After the application is launched, if an --out argument specified a file, the "YARN application report" will be saved as a .json document into the file specified.

Example

/usr/hdp/current/slider-client/bin/./slider start app1

destroy <name> Destroy a (stopped) application instance. Important: This deletes all persistent data.

Example:

/usr/hdp/current/slider-client/bin/./slider destroy app1 

flex <name> [--component component count]* Flex the number of workers in an application instance to the new value. If greater than before, new copies of the component will be requested. If less, component instances will be destroyed.

This operation has a return value of 0 if the change was submitted. Changes are not immediate and depend on the availability of resources in the YARN cluster

It returns -1 if there is no running application instance.

Examples:

slider flex app1 --component worker 8 --filesystem hdfs://<host>:<port>
slider flex app1 --component master 2 --filesystem hdfs://<host>:<port>

For more information on Slider CLI commands, see the Apache Slider documentation.

You can use the Slider help command to display a list of available commands.

[root@node-1 /]# /usr/hdp/current/slider-client/bin/./slider help
2014-10-31 09:20:10,852 [main] INFO client.SliderClient - Usage: slider 
COMMAND [options] where COMMAND is one of
 am-suicide        Tell the Slider Application Master to simulate a 
                   process failure by terminating itself
 build             Build a Slider cluster specification -but do not start it
 create            Create a live Slider application
 update            Update template for a Slider application
 destroy           Destroy a frozen Slider application)
 diagnostics       Diagnose the configuration of the running slider 
                   application and slider client
 exists            Probe for an application running
 flex              Flex a Slider application
 stop              Stop a running application
 help              Print help information
 install-package   Install the application package in the home directory 
                   under sub-folder packages
 install-keytab    Install the Kerberos keytab file in the sub-folder 
                   'keytabs' of the user's Slider base directory
 kill-container    Kill a container in the application
 list              List running Slider applications
 registry          Query the registry of a YARN application
 resolve           Query the registry of a YARN application
 status            Get the status of an application
 start             Start a stopped application
 version           Print the Slider version information
Most commands print help when invoked without parameters
2014-10-31 09:20:10,856 [main] INFO util.ExitUtil - Exiting with status 0

Most commands display Help when invoked without parameters, similar to the usage statement shown below:

[root@node-1 /]# slider status
2014-10-31 09:45:11,817 [main] ERROR main.ServiceLauncher - org.apache.
slider.core.exceptions.BadCommandArgumentsException: Not enough arguments 
for action: status Expected minimum 1 but got 0
Usage: slider status <application>
 --manager <manager>                Binding (usually hostname:port) 
                                          of the YARN resource manager 
                                          (optional)
 --basepath <basePath>              Slider base path on the filesystem 
                                          (optional)
 --filesystem <filesystemBinding>   Filesystem Binding (optional)
 -D <definitions>                   Definitions (optional)
 --debug                                  Debug mode (optional)
 -S <sysprops>                      System properties in the form name 
                                          value These are set after the JVM is 
                                          started. (optional)
 --out <output>                     Output file for the configuration 
                                          data (optional)

2014-10-31 09:45:11,826 [main] INFO util.ExitUtil - Exiting with status 40 
[root@node-1 /]#

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