org.apache.flink.runtime.taskmanager

Class Task

java.lang.Object

org.apache.flink.runtime.taskmanager.Task

All Implemented Interfaces:

Runnable, PartitionProducerStateProvider, TaskSlotPayload, TaskActions

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

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 TaskInvokable 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

Modifier and Type	Class and Description
static class	Task.NotifyCheckpointOperation Various operation of notify checkpoint.

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, List<ResultPartitionDeploymentDescriptor> resultPartitionDeploymentDescriptors, List<InputGateDeploymentDescriptor> inputGateDeploymentDescriptors, MemoryManager memManager, SharedResources sharedResources, IOManager ioManager, ShuffleEnvironment<?,?> shuffleEnvironment, KvStateService kvStateService, BroadcastVariableManager bcVarManager, TaskEventDispatcher taskEventDispatcher, ExternalResourceInfoProvider externalResourceInfoProvider, TaskStateManager taskStateManager, TaskManagerActions taskManagerActions, InputSplitProvider inputSplitProvider, CheckpointResponder checkpointResponder, TaskOperatorEventGateway operatorCoordinatorEventGateway, GlobalAggregateManager aggregateManager, LibraryCacheManager.ClassLoaderHandle classLoaderHandle, FileCache fileCache, TaskManagerRuntimeInfo taskManagerConfig, TaskMetricGroup metricGroup, PartitionProducerStateChecker partitionProducerStateChecker, Executor executor, ChannelStateWriteRequestExecutorFactory channelStateExecutorFactory) 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	deliverOperatorEvent(OperatorID operator, SerializedValue<OperatorEvent> evt) Dispatches an operator event to the invokable task.
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.
Configuration	getJobConfiguration()
JobID	getJobID()
JobVertexID	getJobVertexId()
TaskMetricGroup	getMetricGroup()
Configuration	getTaskConfiguration()
TaskInfo	getTaskInfo()
CompletableFuture<ExecutionState>	getTerminationFuture()
boolean	isBackPressured()
boolean	isCanceledOrFailed() Checks whether the task has failed, is canceled, or is being canceled at the moment.
static void	logTaskThreadStackTrace(Thread thread, String taskName, long timeoutMs, String action)
void	notifyCheckpointAborted(long checkpointID, long latestCompletedCheckpointId)
void	notifyCheckpointComplete(long checkpointID)
void	notifyCheckpointSubsumed(long checkpointID)
void	requestPartitionProducerState(IntermediateDataSetID intermediateDataSetId, ResultPartitionID resultPartitionId, 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) 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,
            List<ResultPartitionDeploymentDescriptor> resultPartitionDeploymentDescriptors,
            List<InputGateDeploymentDescriptor> inputGateDeploymentDescriptors,
            MemoryManager memManager,
            SharedResources sharedResources,
            IOManager ioManager,
            ShuffleEnvironment<?,?> shuffleEnvironment,
            KvStateService kvStateService,
            BroadcastVariableManager bcVarManager,
            TaskEventDispatcher taskEventDispatcher,
            ExternalResourceInfoProvider externalResourceInfoProvider,
            TaskStateManager taskStateManager,
            TaskManagerActions taskManagerActions,
            InputSplitProvider inputSplitProvider,
            CheckpointResponder checkpointResponder,
            TaskOperatorEventGateway operatorCoordinatorEventGateway,
            GlobalAggregateManager aggregateManager,
            LibraryCacheManager.ClassLoaderHandle classLoaderHandle,
            FileCache fileCache,
            TaskManagerRuntimeInfo taskManagerConfig,
            @Nonnull
            TaskMetricGroup metricGroup,
            PartitionProducerStateChecker partitionProducerStateChecker,
            Executor executor,
            ChannelStateWriteRequestExecutorFactory channelStateExecutorFactory)

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 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 TaskInfo getTaskInfo()

getJobConfiguration

public Configuration getJobConfiguration()

getTaskConfiguration

public 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()

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.

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

Throws:

IOException

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,
                                          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)

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.

notifyCheckpointComplete

public void notifyCheckpointComplete(long checkpointID)

notifyCheckpointAborted

public void notifyCheckpointAborted(long checkpointID,
                                    long latestCompletedCheckpointId)

notifyCheckpointSubsumed

public void notifyCheckpointSubsumed(long checkpointID)

deliverOperatorEvent

public void deliverOperatorEvent(OperatorID operator,
                                 SerializedValue<OperatorEvent> evt)
                          throws FlinkException

Dispatches an operator event to the invokable task.

If the event delivery did not succeed, this method throws an exception. Callers can use that exception for error reporting, but need not react with failing this task (this method takes care of that).

Throws:

FlinkException - This method throws exceptions indicating the reason why delivery did not succeed.

toString

public String toString()

Overrides:

toString in class Object

logTaskThreadStackTrace

public static void logTaskThreadStackTrace(Thread thread,
                                           String taskName,
                                           long timeoutMs,
                                           String action)