org.apache.flink.runtime.instance

Class SharedSlot

java.lang.Object

org.apache.flink.runtime.instance.Slot

org.apache.flink.runtime.instance.SharedSlot

public class SharedSlot
extends Slot

This class represents a shared slot. A shared slot can have multiple SimpleSlot instances within itself. This allows to schedule multiple tasks simultaneously, enabling Flink's streaming capabilities. IMPORTANT: This class contains no synchronization. Thus, the caller has to guarantee proper synchronization. In the current implementation, all concurrently modifying operations are passed through a SlotSharingGroupAssignment object which is responsible for synchronization.

Field Summary

Fields inherited from class org.apache.flink.runtime.instance.Slot

ALLOCATED_AND_ALIVE, CANCELLED, instance, jobID, RELEASED, slotNumber, status, STATUS_UPDATER

Constructor Summary

Constructors

Constructor and Description
SharedSlot(JobID jobID, Instance instance, int slotNumber, SlotSharingGroupAssignment assignmentGroup, SharedSlot parent, AbstractID groupID)

Method Summary

Methods

Modifier and Type	Method and Description
SharedSlot	allocateSharedSlot(AbstractID jID)
SimpleSlot	allocateSubSlot(AbstractID jID) Creates a new sub slot if the slot is not dead, yet.
void	cancel()
void	disposeChild(SimpleSlot slot) Disposes the given sub slot.
int	freeSubSlot(Slot slot) Removes the simple slot from the SharedSlot.
int	getNumberLeaves()
Set<Slot>	getSubSlots()
void	releaseSlot() Release this shared slot.
String	toString()

Methods inherited from class org.apache.flink.runtime.instance.Slot

getGroupID, getInstance, getJobID, getParent, getRoot, getSlotNumber, hierarchy, isAlive, isCanceled, isDead, isDisposed, isReleased, markCancelled, markDead, markDisposed, markReleased

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

SharedSlot

public SharedSlot(JobID jobID,
          Instance instance,
          int slotNumber,
          SlotSharingGroupAssignment assignmentGroup,
          SharedSlot parent,
          AbstractID groupID)

Method Detail

getSubSlots

public Set<Slot> getSubSlots()

freeSubSlot

public int freeSubSlot(Slot slot)

Removes the simple slot from the SharedSlot. Should only be called through the SlotSharingGroupAssignment attribute assignmnetGroup.

Parameters:

slot - slot to be removed from the set of sub slots.

Returns:

Number of remaining sub slots

getNumberLeaves

public int getNumberLeaves()

Specified by:

getNumberLeaves in class Slot

cancel

public void cancel()

Specified by:

cancel in class Slot

releaseSlot

public void releaseSlot()

Release this shared slot. In order to do this: 1. Cancel and release all sub slots atomically with respect to the assigned assignment group. 2. Set the state of the shared slot to be cancelled. 3. Dispose the shared slot (returning the slot to the instance). After cancelAndReleaseSubSlots, the shared slot is marked to be dead. This prevents further sub slot creation by the scheduler.

Specified by:

releaseSlot in class Slot

allocateSubSlot

public SimpleSlot allocateSubSlot(AbstractID jID)

Creates a new sub slot if the slot is not dead, yet. This method should only be called from the assignment group instance to guarantee synchronization.

Parameters:

jID - id to identify tasks which can be deployed in this sub slot

Returns:

new sub slot if the shared slot is still alive, otherwise null

allocateSharedSlot

public SharedSlot allocateSharedSlot(AbstractID jID)

disposeChild

public void disposeChild(SimpleSlot slot)

Disposes the given sub slot. This is done by the means of the assignmentGroup in order to synchronize the method. If the disposed slot was the last sub slot, then the shared slot is marked to be cancelled and is disposed/returned to the owning instance.

Parameters:

slot - sub slot which shall be removed from the shared slot

toString

public String toString()

Overrides:

toString in class Slot