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== [[LauncherBackend]] LauncherBackend

LauncherBackend is the <> of <> that can <>.

[[contract]] .LauncherBackend Contract (Abstract Methods Only) [cols="1m,3",options="header",width="100%"] |=== | Method | Description

| conf a| [[conf]]

[source, scala]

conf: SparkConf[]

Used exclusively when LauncherBackend is requested to <> (to access[spark.launcher.port] and[spark.launcher.secret] configuration properties)

| onStopRequest a| [[onStopRequest]]

[source, scala]

onStopRequest(): Unit

Handles stop requests (to stop the Spark application as gracefully as possible)

Used exclusively when LauncherBackend is requested to <>


[[creating-instance]] LauncherBackend takes no arguments to be created.

NOTE: LauncherBackend is a Scala abstract class and cannot be <> directly. It is created indirectly for the <>.

[[internal-registries]] .LauncherBackend's Internal Properties (e.g. Registries, Counters and Flags) [cols="1m,3",options="header",width="100%"] |=== | Name | Description

| _isConnected a| [[_isConnected]][[isConnected]] Flag that says whether...FIXME (true) or not (false)

Default: false

Used when...FIXME

| clientThread a| [[clientThread]] Java's[java.lang.Thread]

Used when...FIXME

| connection a| [[connection]] BackendConnection

Used when...FIXME

| lastState a| [[lastState]] SparkAppHandle.State

Used when...FIXME


[[implementations]] LauncherBackend is <> (as an anonymous class) for the following:

  • Spark on YARN's <>

  • Spark local's <>

  • Spark on Mesos' <>

  • Spark Standalone's <>

=== [[close]] Closing -- close Method

[source, scala]

close(): Unit


NOTE: close is used when...FIXME

=== [[connect]] Connecting -- connect Method

[source, scala]

connect(): Unit



connect is used when:

  • Spark Standalone's StandaloneSchedulerBackend is requested to <> (in client deploy mode)

  • Spark local's LocalSchedulerBackend is <>

  • Spark on Mesos' MesosCoarseGrainedSchedulerBackend is requested to <> (in client deploy mode)

* Spark on YARN's Client is requested to <>

=== [[fireStopRequest]] fireStopRequest Internal Method

[source, scala]

fireStopRequest(): Unit


NOTE: fireStopRequest is used exclusively when BackendConnection is requested to handle a Stop message.

=== [[onDisconnected]] Handling Disconnects From Scheduling Backend -- onDisconnected Method

[source, scala]

onDisconnected(): Unit

onDisconnected does nothing by default and is expected to be overriden by <>.

NOTE: onDisconnected is used when...FIXME

=== [[setAppId]] setAppId Method

[source, scala]

setAppId(appId: String): Unit


NOTE: setAppId is used when...FIXME

=== [[setState]] setState Method

[source, scala]

setState(state: SparkAppHandle.State): Unit


NOTE: setState is used when...FIXME