org.apache.flink.runtime.taskmanager

Class Task

java.lang.Object

org.apache.flink.runtime.taskmanager.Task

All Implemented Interfaces:

Runnable, PartitionProducerStateProvider, CheckpointListener, BackPressureSampleableTask, TaskSlotPayload, TaskActions

public class Task
extends Object
implements Runnable, TaskSlotPayload, TaskActions, PartitionProducerStateProvider, CheckpointListener, BackPressureSampleableTask

The Task represents one execution of a parallel subtask on a TaskManager. A Task wraps a Flink operator (which may be a user function) and runs it, providing all services necessary for example to consume input data, produce its results (intermediate result partitions) and communicate with the JobManager.

The Flink operators (implemented as subclasses of AbstractInvokable have only data readers, writers, and certain event callbacks. The task connects those to the network stack and actor messages, and tracks the state of the execution and handles exceptions.

Tasks have no knowledge about how they relate to other tasks, or whether they are the first attempt to execute the task, or a repeated attempt. All of that is only known to the JobManager. All the task knows are its own runnable code, the task's configuration, and the IDs of the intermediate results to consume and produce (if any).

Each Task is run by one dedicated thread.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.runtime.io.network.partition.PartitionProducerStateProvider

PartitionProducerStateProvider.ResponseHandle

Constructor Summary

Constructors

Constructor and Description

Task(JobInformation jobInformation, TaskInformation taskInformation, ExecutionAttemptID executionAttemptID, AllocationID slotAllocationId, int subtaskIndex, int attemptNumber, Collection<ResultPartitionDeploymentDescriptor> resultPartitionDeploymentDescriptors, Collection<InputGateDeploymentDescriptor> inputGateDeploymentDescriptors, int targetSlotNumber, MemoryManager memManager, IOManager ioManager, ShuffleEnvironment<?,?> shuffleEnvironment, KvStateService kvStateService, BroadcastVariableManager bcVarManager, TaskEventDispatcher taskEventDispatcher, TaskStateManager taskStateManager, TaskManagerActions taskManagerActions, InputSplitProvider inputSplitProvider, CheckpointResponder checkpointResponder, GlobalAggregateManager aggregateManager, BlobCacheService blobService, LibraryCacheManager libraryCache, FileCache fileCache, TaskManagerRuntimeInfo taskManagerConfig, TaskMetricGroup metricGroup, ResultPartitionConsumableNotifier resultPartitionConsumableNotifier, PartitionProducerStateChecker partitionProducerStateChecker, Executor executor) IMPORTANT: This constructor may not start any work that would need to be undone in the case of a failing task deployment.

Method Summary

Modifier and Type	Method and Description
void	cancelExecution() Cancels the task execution.
void	failExternally(Throwable cause) Marks task execution failed for an external reason (a reason other than the task code itself throwing an exception).
AccumulatorRegistry	getAccumulatorRegistry()
AllocationID	getAllocationId()
Thread	getExecutingThread()
ExecutionAttemptID	getExecutionId()
ExecutionState	getExecutionState() Returns the current execution state of the task.
Throwable	getFailureCause() If the task has failed, this method gets the exception that caused this task to fail.
org.apache.flink.configuration.Configuration	getJobConfiguration()
org.apache.flink.api.common.JobID	getJobID()
JobVertexID	getJobVertexId()
TaskMetricGroup	getMetricGroup()
org.apache.flink.configuration.Configuration	getTaskConfiguration()
org.apache.flink.api.common.TaskInfo	getTaskInfo()
CompletableFuture<ExecutionState>	getTerminationFuture()
boolean	isBackPressured()
boolean	isCanceledOrFailed() Checks whether the task has failed, is canceled, or is being canceled at the moment.
boolean	isRunning()
void	notifyCheckpointComplete(long checkpointID) This method is called as a notification once a distributed checkpoint has been completed.
void	requestPartitionProducerState(IntermediateDataSetID intermediateDataSetId, ResultPartitionID resultPartitionId, java.util.function.Consumer<? super PartitionProducerStateProvider.ResponseHandle> responseConsumer) Trigger the producer execution state request.
void	run() The core work method that bootstraps the task and executes its code.
static void	setupPartitionsAndGates(ResultPartitionWriter[] producedPartitions, InputGate[] inputGates)
void	startTaskThread() Starts the task's thread.
String	toString()
void	triggerCheckpointBarrier(long checkpointID, long checkpointTimestamp, CheckpointOptions checkpointOptions, boolean advanceToEndOfEventTime) Calls the invokable to trigger a checkpoint.

Methods inherited from class java.lang.Object

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

Constructor Detail

Task

public Task(JobInformation jobInformation,
            TaskInformation taskInformation,
            ExecutionAttemptID executionAttemptID,
            AllocationID slotAllocationId,
            int subtaskIndex,
            int attemptNumber,
            Collection<ResultPartitionDeploymentDescriptor> resultPartitionDeploymentDescriptors,
            Collection<InputGateDeploymentDescriptor> inputGateDeploymentDescriptors,
            int targetSlotNumber,
            MemoryManager memManager,
            IOManager ioManager,
            ShuffleEnvironment<?,?> shuffleEnvironment,
            KvStateService kvStateService,
            BroadcastVariableManager bcVarManager,
            TaskEventDispatcher taskEventDispatcher,
            TaskStateManager taskStateManager,
            TaskManagerActions taskManagerActions,
            InputSplitProvider inputSplitProvider,
            CheckpointResponder checkpointResponder,
            GlobalAggregateManager aggregateManager,
            BlobCacheService blobService,
            LibraryCacheManager libraryCache,
            FileCache fileCache,
            TaskManagerRuntimeInfo taskManagerConfig,
            @Nonnull
            TaskMetricGroup metricGroup,
            ResultPartitionConsumableNotifier resultPartitionConsumableNotifier,
            PartitionProducerStateChecker partitionProducerStateChecker,
            Executor executor)

IMPORTANT: This constructor may not start any work that would need to be undone in the case of a failing task deployment.

Method Detail

getJobID

public org.apache.flink.api.common.JobID getJobID()

Specified by:

getJobID in interface TaskSlotPayload

getJobVertexId

public JobVertexID getJobVertexId()

getExecutionId

public ExecutionAttemptID getExecutionId()

Specified by:

getExecutionId in interface TaskSlotPayload

getAllocationId

public AllocationID getAllocationId()

Specified by:

getAllocationId in interface TaskSlotPayload

getTaskInfo

public org.apache.flink.api.common.TaskInfo getTaskInfo()

getJobConfiguration

public org.apache.flink.configuration.Configuration getJobConfiguration()

getTaskConfiguration

public org.apache.flink.configuration.Configuration getTaskConfiguration()

getAccumulatorRegistry

public AccumulatorRegistry getAccumulatorRegistry()

getMetricGroup

public TaskMetricGroup getMetricGroup()

getExecutingThread

public Thread getExecutingThread()

getTerminationFuture

public CompletableFuture<ExecutionState> getTerminationFuture()

Specified by:

getTerminationFuture in interface TaskSlotPayload

isBackPressured

public boolean isBackPressured()

Specified by:

isBackPressured in interface BackPressureSampleableTask

getExecutionState

public ExecutionState getExecutionState()

Returns the current execution state of the task.

Returns:

The current execution state of the task.

isCanceledOrFailed

public boolean isCanceledOrFailed()

Checks whether the task has failed, is canceled, or is being canceled at the moment.

Returns:

True is the task in state FAILED, CANCELING, or CANCELED, false otherwise.

isRunning

public boolean isRunning()

Specified by:

isRunning in interface BackPressureSampleableTask

getFailureCause

public Throwable getFailureCause()

If the task has failed, this method gets the exception that caused this task to fail. Otherwise this method returns null.

Returns:

The exception that caused the task to fail, or null, if the task has not failed.

startTaskThread

public void startTaskThread()

Starts the task's thread.

run

public void run()

The core work method that bootstraps the task and executes its code.

Specified by:

run in interface Runnable

setupPartitionsAndGates

@VisibleForTesting
public static void setupPartitionsAndGates(ResultPartitionWriter[] producedPartitions,
                                                              InputGate[] inputGates)
                                                       throws IOException,
                                                              InterruptedException

Throws:

IOException

InterruptedException

cancelExecution

public void cancelExecution()

Cancels the task execution. If the task is already in a terminal state (such as FINISHED, CANCELED, FAILED), or if the task is already canceling this does nothing. Otherwise it sets the state to CANCELING, and, if the invokable code is running, starts an asynchronous thread that aborts that code.

This method never blocks.

failExternally

public void failExternally(Throwable cause)

Marks task execution failed for an external reason (a reason other than the task code itself throwing an exception). If the task is already in a terminal state (such as FINISHED, CANCELED, FAILED), or if the task is already canceling this does nothing. Otherwise it sets the state to FAILED, and, if the invokable code is running, starts an asynchronous thread that aborts that code.

This method never blocks.

Specified by:

failExternally in interface TaskSlotPayload

Specified by:

failExternally in interface TaskActions

Parameters:

cause - of the failure

requestPartitionProducerState

public void requestPartitionProducerState(IntermediateDataSetID intermediateDataSetId,
                                          ResultPartitionID resultPartitionId,
                                          java.util.function.Consumer<? super PartitionProducerStateProvider.ResponseHandle> responseConsumer)

Description copied from interface: PartitionProducerStateProvider

Trigger the producer execution state request.

Specified by:

requestPartitionProducerState in interface PartitionProducerStateProvider

Parameters:

intermediateDataSetId - ID of the parent intermediate data set.

resultPartitionId - ID of the result partition to check. This identifies the producing execution and partition.

responseConsumer - consumer for the response handle.

triggerCheckpointBarrier

public void triggerCheckpointBarrier(long checkpointID,
                                     long checkpointTimestamp,
                                     CheckpointOptions checkpointOptions,
                                     boolean advanceToEndOfEventTime)

Calls the invokable to trigger a checkpoint.

Parameters:

checkpointID - The ID identifying the checkpoint.

checkpointTimestamp - The timestamp associated with the checkpoint.

checkpointOptions - Options for performing this checkpoint.

advanceToEndOfEventTime - Flag indicating if the source should inject a MAX_WATERMARK in the pipeline to fire any registered event-time timers.

notifyCheckpointComplete

public void notifyCheckpointComplete(long checkpointID)

Description copied from interface: CheckpointListener

This method is called as a notification once a distributed checkpoint has been completed. Note that any exception during this method will not cause the checkpoint to fail any more.

Specified by:

notifyCheckpointComplete in interface CheckpointListener

Parameters:

checkpointID - The ID of the checkpoint that has been completed.

toString

public String toString()

Overrides:

toString in class Object