rootPool: PoolSchedulable Builders
SchedulableBuilder is a contract of schedulable builders that operate on a pool of TaskSetManagers (from an owning TaskSchedulerImpl).
Schedulable builders can build pools and add new Schedulable entities to the pool.
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Note
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A SchedulableBuilder is created when TaskSchedulerImpl is being initialized. You can select the SchedulableBuilder to use by spark.scheduler.mode setting.
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Spark comes with two implementations of the SchedulableBuilder Contract:
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FIFOSchedulableBuilder - the default
SchedulableBuilder
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Note
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SchedulableBuilder is a private[spark] Scala trait. You can find the sources in org.apache.spark.scheduler.SchedulableBuilder.
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SchedulableBuilder Contract
Every SchedulableBuilder provides the following services:
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It manages a root pool.
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It can build pools.
Root Pool (rootPool method)
rootPool method returns a Pool (of Schedulables).
This is the data structure managed (aka wrapped) by SchedulableBuilders.
Build Pools (buildPools method)
buildPools(): Unit|
Note
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It is exclusively called by TaskSchedulerImpl.initialize. |
Adding Schedulable (to Pool) (addTaskSetManager method)
addTaskSetManager(manager: Schedulable, properties: Properties): UnitaddTaskSetManager registers the manager Schedulable (with additional properties) to the rootPool.
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Note
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addTaskSetManager is exclusively used by TaskSchedulerImpl to submit a TaskSetManager for a stage for execution.
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