org.apache.flink.runtime.taskmanager

Class Task

java.lang.Object

org.apache.flink.runtime.taskmanager.Task

All Implemented Interfaces:

Runnable

public class Task
extends Object
implements Runnable

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.

Constructor Summary

Constructors

Constructor and Description

Task(TaskDeploymentDescriptor tdd, MemoryManager memManager, IOManager ioManager, NetworkEnvironment networkEnvironment, BroadcastVariableManager bcVarManager, ActorGateway taskManagerActor, ActorGateway jobManagerActor, scala.concurrent.duration.FiniteDuration actorAskTimeout, LibraryCacheManager libraryCache, FileCache fileCache, TaskManagerRuntimeInfo taskManagerConfig) 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()
SingleInputGate[]	getAllInputGates()
ResultPartitionWriter[]	getAllWriters()
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.
SingleInputGate	getInputGateById(IntermediateDataSetID id)
Configuration	getJobConfiguration()
JobID	getJobID()
JobVertexID	getJobVertexId()
ResultPartition[]	getProducedPartitions()
Configuration	getTaskConfiguration()
TaskInfo	getTaskInfo()
boolean	isCanceledOrFailed() Checks whether the task has failed, is canceled, or is being canceled at the moment.
void	notifyCheckpointComplete(long checkpointID)
void	onPartitionStateUpdate(IntermediateDataSetID resultId, IntermediateResultPartitionID partitionId, ExecutionState partitionState) Answer to a partition state check issued after a failed partition request.
void	registerExecutionListener(ActorGateway listener)
void	run() The core work method that bootstraps the task and executes it code
void	startTaskThread() Starts the task's thread.
void	stopExecution() Stops the executing task by calling StoppableTask.stop().
String	toString()
void	triggerCheckpointBarrier(long checkpointID, long checkpointTimestamp) Calls the invokable to trigger a checkpoint, if the invokable implements the interface StatefulTask.

Methods inherited from class java.lang.Object

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

Constructor Detail

Task

public Task(TaskDeploymentDescriptor tdd,
            MemoryManager memManager,
            IOManager ioManager,
            NetworkEnvironment networkEnvironment,
            BroadcastVariableManager bcVarManager,
            ActorGateway taskManagerActor,
            ActorGateway jobManagerActor,
            scala.concurrent.duration.FiniteDuration actorAskTimeout,
            LibraryCacheManager libraryCache,
            FileCache fileCache,
            TaskManagerRuntimeInfo taskManagerConfig)

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()

getJobVertexId

public JobVertexID getJobVertexId()

getExecutionId

public ExecutionAttemptID getExecutionId()

getTaskInfo

public TaskInfo getTaskInfo()

getJobConfiguration

public Configuration getJobConfiguration()

getTaskConfiguration

public Configuration getTaskConfiguration()

getAllWriters

public ResultPartitionWriter[] getAllWriters()

getAllInputGates

public SingleInputGate[] getAllInputGates()

getProducedPartitions

public ResultPartition[] getProducedPartitions()

getInputGateById

public SingleInputGate getInputGateById(IntermediateDataSetID id)

getAccumulatorRegistry

public AccumulatorRegistry getAccumulatorRegistry()

getExecutingThread

public Thread getExecutingThread()

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 it code

Specified by:

run in interface Runnable

stopExecution

public void stopExecution()
                   throws UnsupportedOperationException

Stops the executing task by calling StoppableTask.stop().

This method never blocks.

Throws:

UnsupportedOperationException - if the AbstractInvokable does not implement StoppableTask

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.

registerExecutionListener

public void registerExecutionListener(ActorGateway listener)

triggerCheckpointBarrier

public void triggerCheckpointBarrier(long checkpointID,
                                     long checkpointTimestamp)

Calls the invokable to trigger a checkpoint, if the invokable implements the interface StatefulTask.

Parameters:

checkpointID - The ID identifying the checkpoint.

checkpointTimestamp - The timestamp associated with the checkpoint.

notifyCheckpointComplete

public void notifyCheckpointComplete(long checkpointID)

onPartitionStateUpdate

public void onPartitionStateUpdate(IntermediateDataSetID resultId,
                                   IntermediateResultPartitionID partitionId,
                                   ExecutionState partitionState)
                            throws IOException,
                                   InterruptedException

Answer to a partition state check issued after a failed partition request.

Throws:

IOException

InterruptedException

toString

public String toString()

Overrides:

toString in class Object