StreamTask (flink-streaming-java 1.8.1 API)

java.lang.Object
- org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
- - org.apache.flink.streaming.runtime.tasks.StreamTask<OUT,OP>

类型参数:

OUT -

OP -

所有已实现的接口:

AsyncExceptionHandler

直接已知子类:

OneInputStreamTask, SourceStreamTask, TwoInputStreamTask
```
@Internal
public abstract class StreamTask<OUT,OP extends StreamOperator<OUT>>
extends org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
implements AsyncExceptionHandler
```
Base class for all streaming tasks. A task is the unit of local processing that is deployed and executed by the TaskManagers. Each task runs one or more StreamOperators which form the Task's operator chain. Operators that are chained together execute synchronously in the same thread and hence on the same stream partition. A common case for these chains are successive map/flatmap/filter tasks.
The task chain contains one "head" operator and multiple chained operators. The StreamTask is specialized for the type of the head operator: one-input and two-input tasks, as well as for sources, iteration heads and iteration tails.
The Task class deals with the setup of the streams read by the head operator, and the streams produced by the operators at the ends of the operator chain. Note that the chain may fork and thus have multiple ends.
The life cycle of the task is set up as follows:
```
  -- setInitialState -> provides state of all operators in the chain

  -- invoke()
        |
        +----> Create basic utils (config, etc) and load the chain of operators
        +----> operators.setup()
        +----> task specific init()
        +----> initialize-operator-states()
        +----> open-operators()
        +----> run()
        +----> close-operators()
        +----> dispose-operators()
        +----> common cleanup
        +----> task specific cleanup()
 
```
The StreamTask has a lock object called lock. All calls to methods on a StreamOperator must be synchronized on this lock object to ensure that no methods are called concurrently.

嵌套类概要

嵌套类
限定符和类型	类和说明
`protected static class`	`StreamTask.AsyncCheckpointRunnable` This runnable executes the asynchronous parts of all involved backend snapshots for the subtask.

字段概要

字段
限定符和类型	字段和说明
`protected StreamConfig`	`configuration` The configuration of this streaming task.
`protected OP`	`headOperator` the head operator that consumes the input streams of this task.
`protected OperatorChain<OUT,OP>`	`operatorChain` The chain of operators executed by this task.
`protected org.apache.flink.runtime.state.StateBackend`	`stateBackend` Our state backend.
`protected ProcessingTimeService`	`timerService` The internal `ProcessingTimeService` used to define the current processing time (default = `System.currentTimeMillis()`) and register timers for tasks to be executed in the future.
`static ThreadGroup`	`TRIGGER_THREAD_GROUP` The thread group that holds all trigger timer threads.

构造器概要

构造器
限定符	构造器和说明
`protected`	`StreamTask(org.apache.flink.runtime.execution.Environment env)` Constructor for initialization, possibly with initial state (recovery / savepoint / etc).
`protected`	`StreamTask(org.apache.flink.runtime.execution.Environment environment, ProcessingTimeService timeProvider)` Constructor for initialization, possibly with initial state (recovery / savepoint / etc).

方法概要

所有方法静态方法实例方法抽象方法具体方法
限定符和类型	方法和说明
`void`	`abortCheckpointOnBarrier(long checkpointId, Throwable cause)`
`void`	`cancel()`
`protected abstract void`	`cancelTask()`
`protected abstract void`	`cleanup()`
`protected CheckpointExceptionHandlerFactory`	`createCheckpointExceptionHandlerFactory()`
`static <OUT> List<org.apache.flink.runtime.io.network.api.writer.RecordWriter<org.apache.flink.runtime.plugable.SerializationDelegate<StreamRecord<OUT>>>>`	`createRecordWriters(StreamConfig configuration, org.apache.flink.runtime.execution.Environment environment)`
`StreamTaskStateInitializer`	`createStreamTaskStateInitializer()`
`protected void`	`finalize()` The finalize method shuts down the timer.
`Map<String,org.apache.flink.api.common.accumulators.Accumulator<?,?>>`	`getAccumulatorMap()`
`ExecutorService`	`getAsyncOperationsThreadPool()`
`org.apache.flink.core.fs.CloseableRegistry`	`getCancelables()`
`Object`	`getCheckpointLock()` Gets the lock object on which all operations that involve data and state mutation have to lock.
`org.apache.flink.runtime.state.CheckpointStorage`	`getCheckpointStorage()`
`StreamConfig`	`getConfiguration()`
`String`	`getName()` Gets the name of the task, in the form "taskname (2/5)".
`ProcessingTimeService`	`getProcessingTimeService()` Returns the `ProcessingTimeService` responsible for telling the current processing time and registering timers.
`StreamStatusMaintainer`	`getStreamStatusMaintainer()`
`void`	`handleAsyncException(String message, Throwable exception)` Handles an exception thrown by another thread (e.g. a TriggerTask), other than the one executing the main task by failing the task entirely.
`protected abstract void`	`init()`
`void`	`invoke()`
`boolean`	`isCanceled()`
`boolean`	`isRunning()`
`void`	`notifyCheckpointComplete(long checkpointId)`
`protected abstract void`	`run()`
`String`	`toString()`
`boolean`	`triggerCheckpoint(org.apache.flink.runtime.checkpoint.CheckpointMetaData checkpointMetaData, org.apache.flink.runtime.checkpoint.CheckpointOptions checkpointOptions)`
`void`	`triggerCheckpointOnBarrier(org.apache.flink.runtime.checkpoint.CheckpointMetaData checkpointMetaData, org.apache.flink.runtime.checkpoint.CheckpointOptions checkpointOptions, org.apache.flink.runtime.checkpoint.CheckpointMetrics checkpointMetrics)`

从类继承的方法 org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
getCurrentNumberOfSubtasks, getEnvironment, getExecutionConfig, getIndexInSubtaskGroup, getJobConfiguration, getTaskConfiguration, getUserCodeClassLoader, setShouldInterruptOnCancel, shouldInterruptOnCancel

从类继承的方法 java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

- 字段详细资料
  - TRIGGER_THREAD_GROUP
```
public static final ThreadGroup TRIGGER_THREAD_GROUP
```
    The thread group that holds all trigger timer threads.
  - headOperator
```
protected OP extends StreamOperator<OUT> headOperator
```
    the head operator that consumes the input streams of this task.
  - operatorChain
```
protected OperatorChain<OUT,OP extends StreamOperator<OUT>> operatorChain
```
    The chain of operators executed by this task.
  - configuration
```
protected final StreamConfig configuration
```
    The configuration of this streaming task.
  - stateBackend
```
protected org.apache.flink.runtime.state.StateBackend stateBackend
```
    Our state backend. We use this to create checkpoint streams and a keyed state backend.
  - timerService
```
protected ProcessingTimeService timerService
```
    The internal ProcessingTimeService used to define the current processing time (default = System.currentTimeMillis()) and register timers for tasks to be executed in the future.
- 构造器详细资料
  - StreamTask
```
protected StreamTask(org.apache.flink.runtime.execution.Environment env)
```
    Constructor for initialization, possibly with initial state (recovery / savepoint / etc).
    
    参数:
    
    env - The task environment for this task.
  - StreamTask
```
protected StreamTask(org.apache.flink.runtime.execution.Environment environment,
                     @Nullable
                     ProcessingTimeService timeProvider)
```
    Constructor for initialization, possibly with initial state (recovery / savepoint / etc).
    This constructor accepts a special ProcessingTimeService. By default (and if null is passes for the time provider) a DefaultTimerService will be used.
    
    参数:
    
    environment - The task environment for this task.
    
    timeProvider - Optionally, a specific time provider to use.
- 方法详细资料
  - init
```
protected abstract void init()
                      throws Exception
```
    抛出:
    
    Exception
  - run
```
protected abstract void run()
                     throws Exception
```
    抛出:
    
    Exception
  - cleanup
```
protected abstract void cleanup()
                         throws Exception
```
    抛出:
    
    Exception
  - cancelTask
```
protected abstract void cancelTask()
                            throws Exception
```
    抛出:
    
    Exception
  - createStreamTaskStateInitializer
```
public StreamTaskStateInitializer createStreamTaskStateInitializer()
```
  - invoke
```
public final void invoke()
                  throws Exception
```
    指定者:
    
    invoke 在类中 org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
    
    抛出:
    
    Exception
  - cancel
```
public final void cancel()
                  throws Exception
```
    覆盖:
    
    cancel 在类中 org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
    
    抛出:
    
    Exception
  - isRunning
```
public final boolean isRunning()
```
  - isCanceled
```
public final boolean isCanceled()
```
  - finalize
```
protected void finalize()
                 throws Throwable
```
    The finalize method shuts down the timer. This is a fail-safe shutdown, in case the original shutdown method was never called.
    This should not be relied upon! It will cause shutdown to happen much later than if manual shutdown is attempted, and cause threads to linger for longer than needed.
    
    覆盖:
    
    finalize 在类中 Object
    
    抛出:
    
    Throwable
  - getName
```
public String getName()
```
    Gets the name of the task, in the form "taskname (2/5)".
    
    返回:
    
    The name of the task.
  - getCheckpointLock
```
public Object getCheckpointLock()
```
    Gets the lock object on which all operations that involve data and state mutation have to lock.
    
    返回:
    
    The checkpoint lock object.
  - getCheckpointStorage
```
public org.apache.flink.runtime.state.CheckpointStorage getCheckpointStorage()
```
  - getConfiguration
```
public StreamConfig getConfiguration()
```
  - getAccumulatorMap
```
public Map<String,org.apache.flink.api.common.accumulators.Accumulator<?,?>> getAccumulatorMap()
```
  - getStreamStatusMaintainer
```
public StreamStatusMaintainer getStreamStatusMaintainer()
```
  - triggerCheckpoint
```
public boolean triggerCheckpoint(org.apache.flink.runtime.checkpoint.CheckpointMetaData checkpointMetaData,
                                 org.apache.flink.runtime.checkpoint.CheckpointOptions checkpointOptions)
                          throws Exception
```
    覆盖:
    
    triggerCheckpoint 在类中 org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
    
    抛出:
    
    Exception
  - triggerCheckpointOnBarrier
```
public void triggerCheckpointOnBarrier(org.apache.flink.runtime.checkpoint.CheckpointMetaData checkpointMetaData,
                                       org.apache.flink.runtime.checkpoint.CheckpointOptions checkpointOptions,
                                       org.apache.flink.runtime.checkpoint.CheckpointMetrics checkpointMetrics)
                                throws Exception
```
    覆盖:
    
    triggerCheckpointOnBarrier 在类中 org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
    
    抛出:
    
    Exception
  - abortCheckpointOnBarrier
```
public void abortCheckpointOnBarrier(long checkpointId,
                                     Throwable cause)
                              throws Exception
```
    覆盖:
    
    abortCheckpointOnBarrier 在类中 org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
    
    抛出:
    
    Exception
  - getAsyncOperationsThreadPool
```
public ExecutorService getAsyncOperationsThreadPool()
```
  - notifyCheckpointComplete
```
public void notifyCheckpointComplete(long checkpointId)
                              throws Exception
```
    覆盖:
    
    notifyCheckpointComplete 在类中 org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable
    
    抛出:
    
    Exception
  - createCheckpointExceptionHandlerFactory
```
protected CheckpointExceptionHandlerFactory createCheckpointExceptionHandlerFactory()
```
  - getProcessingTimeService
```
public ProcessingTimeService getProcessingTimeService()
```
    Returns the ProcessingTimeService responsible for telling the current processing time and registering timers.
  - handleAsyncException
```
public void handleAsyncException(String message,
                                 Throwable exception)
```
    Handles an exception thrown by another thread (e.g. a TriggerTask), other than the one executing the main task by failing the task entirely.
    In more detail, it 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.
    
    指定者:
    
    handleAsyncException 在接口中 AsyncExceptionHandler
  - toString
```
public String toString()
```
    覆盖:
    
    toString 在类中 Object
  - getCancelables
```
public org.apache.flink.core.fs.CloseableRegistry getCancelables()
```
  - createRecordWriters
```
@VisibleForTesting
public static <OUT> List<org.apache.flink.runtime.io.network.api.writer.RecordWriter<org.apache.flink.runtime.plugable.SerializationDelegate<StreamRecord<OUT>>>> createRecordWriters(StreamConfig configuration,
                                                                                                                                                                                                         org.apache.flink.runtime.execution.Environment environment)
```

类 StreamTask<OUT,OP extends StreamOperator<OUT>>

嵌套类概要

字段概要

构造器概要

方法概要

从类继承的方法 org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable

从类继承的方法 java.lang.Object

字段详细资料

TRIGGER_THREAD_GROUP

headOperator

operatorChain

configuration

stateBackend

timerService

构造器详细资料

StreamTask

StreamTask

方法详细资料

init

run

cleanup

cancelTask

createStreamTaskStateInitializer

invoke

cancel

isRunning

isCanceled

finalize

getName

getCheckpointLock

getCheckpointStorage

getConfiguration

getAccumulatorMap

getStreamStatusMaintainer

triggerCheckpoint

triggerCheckpointOnBarrier

abortCheckpointOnBarrier

getAsyncOperationsThreadPool

notifyCheckpointComplete

createCheckpointExceptionHandlerFactory

getProcessingTimeService

handleAsyncException

toString

getCancelables

createRecordWriters