org.apache.flink.runtime.instance

Class SharedSlot

java.lang.Object

org.apache.flink.runtime.instance.Slot

org.apache.flink.runtime.instance.SharedSlot

All Implemented Interfaces:

LogicalSlot

public class SharedSlot
extends Slot
implements LogicalSlot

This class represents a shared slot. A shared slot can have multiple SimpleSlot instances within itself. This allows to schedule multiple tasks simultaneously to the same resource. Sharing a resource with multiple tasks is crucial for simple pipelined / streamed execution, where both the sender and the receiver are typically active at the same time.

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.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.runtime.jobmaster.LogicalSlot

LogicalSlot.Payload

Field Summary

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

NO_ALLOCATION_ID, NO_SLOT_REQUEST_ID, NO_SLOT_SHARING_GROUP_ID

Fields inherited from interface org.apache.flink.runtime.jobmaster.LogicalSlot

TERMINATED_PAYLOAD

Constructor Summary

Constructors

Constructor and Description
SharedSlot(SlotContext slotContext, SlotOwner owner, SlotSharingGroupAssignment assignmentGroup) Creates a new shared slot that has no parent (is a root slot) and does not belong to any task group.
SharedSlot(SlotOwner owner, TaskManagerLocation location, int slotNumber, TaskManagerGateway taskManagerGateway, SlotSharingGroupAssignment assignmentGroup) Creates a new shared slot that has no parent (is a root slot) and does not belong to any task group.
SharedSlot(SlotOwner owner, TaskManagerLocation location, int slotNumber, TaskManagerGateway taskManagerGateway, SlotSharingGroupAssignment assignmentGroup, SharedSlot parent, AbstractID groupId) Creates a new shared slot that has is a sub-slot of the given parent shared slot, and that belongs to the given task group.

Method Summary

Modifier and Type	Method and Description
AllocationID	getAllocationId() Gets the allocation id of this slot.
Locality	getLocality() Gets the locality of this slot.
int	getNumberLeaves() Gets the number of simple slots that are at the leaves of the tree of slots.
LogicalSlot.Payload	getPayload() Returns the set payload or null if none.
int	getPhysicalSlotNumber() Gets the slot number on the TaskManager.
SlotRequestId	getSlotRequestId() Gets the slot request id uniquely identifying the request with which this slot has been allocated.
SlotSharingGroupId	getSlotSharingGroupId() Gets the slot sharing group id to which this slot belongs.
boolean	hasChildren() Checks whether this shared slot has any sub slots.
boolean	isRootAndEmpty() Checks whether this slot is a root slot that has not yet added any child slots.
CompletableFuture<?>	releaseSlot(Throwable cause) This method cancels and releases the slot and all its sub-slots.
String	toString()
boolean	tryAssignPayload(LogicalSlot.Payload payload) Tries to assign a payload to this slot.

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

equals, getGroupID, getOwner, getParent, getRoot, getRootSlotNumber, getSlotContext, getSlotNumber, getTaskManagerGateway, getTaskManagerID, getTaskManagerLocation, hashCode, hierarchy, isAlive, isCanceled, isReleased

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.flink.runtime.jobmaster.LogicalSlot

getTaskManagerGateway, getTaskManagerLocation, isAlive, releaseSlot

Constructor Detail

SharedSlot

public SharedSlot(SlotOwner owner,
                  TaskManagerLocation location,
                  int slotNumber,
                  TaskManagerGateway taskManagerGateway,
                  SlotSharingGroupAssignment assignmentGroup)

Creates a new shared slot that has no parent (is a root slot) and does not belong to any task group. This constructor is used to create a slot directly from an instance.

Parameters:

owner - The component from which this slot is allocated.

location - The location info of the TaskManager where the slot was allocated from

slotNumber - The number of the slot.

taskManagerGateway - The gateway to communicate with the TaskManager

assignmentGroup - The assignment group that this shared slot belongs to.

SharedSlot

public SharedSlot(SlotOwner owner,
                  TaskManagerLocation location,
                  int slotNumber,
                  TaskManagerGateway taskManagerGateway,
                  SlotSharingGroupAssignment assignmentGroup,
                  @Nullable
                  SharedSlot parent,
                  @Nullable
                  AbstractID groupId)

Creates a new shared slot that has is a sub-slot of the given parent shared slot, and that belongs to the given task group.

Parameters:

owner - The component from which this slot is allocated.

location - The location info of the TaskManager where the slot was allocated from

slotNumber - The number of the slot.

taskManagerGateway - The gateway to communicate with the TaskManager

assignmentGroup - The assignment group that this shared slot belongs to.

parent - The parent slot of this slot.

groupId - The assignment group of this slot.

SharedSlot

public SharedSlot(SlotContext slotContext,
                  SlotOwner owner,
                  SlotSharingGroupAssignment assignmentGroup)

Creates a new shared slot that has no parent (is a root slot) and does not belong to any task group. This constructor is used to create a slot directly from an instance.

Parameters:

slotContext - The slot context of this shared slot

owner - The component from which this slot is allocated.

assignmentGroup - The assignment group that this shared slot belongs to.

Method Detail

getNumberLeaves

public int getNumberLeaves()

Description copied from class: Slot

Gets the number of simple slots that are at the leaves of the tree of slots.

Specified by:

getNumberLeaves in class Slot

Returns:

The number of simple slots at the leaves.

isRootAndEmpty

public boolean isRootAndEmpty()

Checks whether this slot is a root slot that has not yet added any child slots.

Returns:

True, if this slot is a root slot and has not yet added any children, false otherwise.

hasChildren

public boolean hasChildren()

Checks whether this shared slot has any sub slots.

Returns:

True, if the shared slot has sub slots, false otherwise.

getLocality

public Locality getLocality()

Description copied from interface: LogicalSlot

Gets the locality of this slot.

Specified by:

getLocality in interface LogicalSlot

Returns:

locality of this slot

tryAssignPayload

public boolean tryAssignPayload(LogicalSlot.Payload payload)

Description copied from interface: LogicalSlot

Tries to assign a payload to this slot. One can only assign a single payload once.

Specified by:

tryAssignPayload in interface LogicalSlot

Parameters:

payload - to be assigned to this slot.

Returns:

true if the payload could be assigned, otherwise false

getPayload

@Nullable
public LogicalSlot.Payload getPayload()

Description copied from interface: LogicalSlot

Returns the set payload or null if none.

Specified by:

getPayload in interface LogicalSlot

Returns:

Payload of this slot of null if none

releaseSlot

public CompletableFuture<?> releaseSlot(@Nullable
                                        Throwable cause)

Description copied from class: Slot

This method cancels and releases the slot and all its sub-slots. After this method completed successfully, the slot will be in state "released", and the Slot.isReleased() method will return true. If this slot is a simple slot, it will be returned to its instance. If it is a shared slot, it will release all of its sub-slots and release itself.

Specified by:

releaseSlot in interface LogicalSlot

Specified by:

releaseSlot in class Slot

Parameters:

cause - why the slot was released or null if none

Returns:

future which is completed once the slot has been released

getPhysicalSlotNumber

public int getPhysicalSlotNumber()

Description copied from interface: LogicalSlot

Gets the slot number on the TaskManager.

Specified by:

getPhysicalSlotNumber in interface LogicalSlot

Returns:

slot number

getAllocationId

public AllocationID getAllocationId()

Description copied from interface: LogicalSlot

Gets the allocation id of this slot.

Specified by:

getAllocationId in interface LogicalSlot

Returns:

allocation id of this slot

getSlotRequestId

public SlotRequestId getSlotRequestId()

Description copied from interface: LogicalSlot

Gets the slot request id uniquely identifying the request with which this slot has been allocated.

Specified by:

getSlotRequestId in interface LogicalSlot

Returns:

Unique id identifying the slot request with which this slot was allocated

getSlotSharingGroupId

@Nullable
public SlotSharingGroupId getSlotSharingGroupId()

Description copied from interface: LogicalSlot

Gets the slot sharing group id to which this slot belongs.

Specified by:

getSlotSharingGroupId in interface LogicalSlot

Returns:

slot sharing group id of this slot or null, if none.

toString

public String toString()

Overrides:

toString in class Slot