Package org.springframework.core.task

Class SimpleAsyncTaskExecutor

java.lang.Object
org.springframework.util.CustomizableThreadCreator
org.springframework.core.task.SimpleAsyncTaskExecutor
All Implemented Interfaces:
Serializable, AutoCloseable, Executor, AsyncListenableTaskExecutor, AsyncTaskExecutor, TaskExecutor
public class SimpleAsyncTaskExecutor extends CustomizableThreadCreator implements AsyncListenableTaskExecutor, Serializable, AutoCloseable
TaskExecutor implementation that fires up a new Thread for each task, executing it asynchronously. Provides a virtual thread option on JDK 21.

Supports a graceful shutdown through setTaskTerminationTimeout(long), at the expense of task tracking overhead per execution thread at runtime. Supports limiting concurrent threads through setConcurrencyLimit(int). By default, the number of concurrent task executions is unlimited.

NOTE: This implementation does not reuse threads! Consider a thread-pooling TaskExecutor implementation instead, in particular for executing a large number of short-lived tasks. Alternatively, on JDK 21, consider setting setVirtualThreads(boolean) to true.

NOTE: This executor does not participate in context-level lifecycle management. Tasks on handed-off execution threads cannot be centrally stopped and restarted; if such tight lifecycle management is necessary, consider a common ThreadPoolTaskExecutor setup instead.

Since:
2.0
Author:
Juergen Hoeller
See Also:

  • Field Details

  • Constructor Details

    • SimpleAsyncTaskExecutor

      public SimpleAsyncTaskExecutor()
      Create a new SimpleAsyncTaskExecutor with default thread name prefix.

    • SimpleAsyncTaskExecutor

      public SimpleAsyncTaskExecutor(String threadNamePrefix)
      Create a new SimpleAsyncTaskExecutor with the given thread name prefix.
      Parameters:
      threadNamePrefix - the prefix to use for the names of newly created threads

    • SimpleAsyncTaskExecutor

      public SimpleAsyncTaskExecutor(ThreadFactory threadFactory)
      Create a new SimpleAsyncTaskExecutor with the given external thread factory.
      Parameters:
      threadFactory - the factory to use for creating new Threads

  • Method Details

    • setVirtualThreads

      public void setVirtualThreads(boolean virtual)
      Switch this executor to virtual threads. Requires Java 21 or higher.

      The default is false, indicating platform threads. Set this flag to true in order to create virtual threads instead.

      Since:
      6.1

    • setThreadFactory

      public void setThreadFactory(@Nullable ThreadFactory threadFactory)
      Specify an external factory to use for creating new Threads, instead of relying on the local properties of this executor.

      You may specify an inner ThreadFactory bean or also a ThreadFactory reference obtained from JNDI (on a Jakarta EE server) or some other lookup mechanism.

      See Also:

    • getThreadFactory

      @Nullable public final ThreadFactory getThreadFactory()
      Return the external factory to use for creating new Threads, if any.

    • setTaskDecorator

      public void setTaskDecorator(TaskDecorator taskDecorator)
      Specify a custom TaskDecorator to be applied to any Runnable about to be executed.

      Note that such a decorator is not necessarily being applied to the user-supplied Runnable/Callable but rather to the actual execution callback (which may be a wrapper around the user-supplied task).

      The primary use case is to set some execution context around the task's invocation, or to provide some monitoring/statistics for task execution.

      NOTE: Exception handling in TaskDecorator implementations is limited to plain Runnable execution via execute calls. In case of #submit calls, the exposed Runnable will be a FutureTask which does not propagate any exceptions; you might have to cast it and call Future#get to evaluate exceptions.

      Since:
      4.3

    • setTaskTerminationTimeout

      public void setTaskTerminationTimeout(long timeout)
      Specify a timeout (in milliseconds) for task termination when closing this executor. The default is 0, not waiting for task termination at all.

      Note that a concrete >0 timeout specified here will lead to the wrapping of every submitted task into a task-tracking runnable which involves considerable overhead in case of a high number of tasks. However, for a modest level of submissions with longer-running tasks, this is feasible in order to arrive at a graceful shutdown.

      Note that SimpleAsyncTaskExecutor does not participate in a coordinated lifecycle stop but rather just awaits task termination on close().

      Parameters:
      timeout - the timeout in milliseconds
      Since:
      6.1
      See Also:
      • close()
      • org.springframework.scheduling.concurrent.ExecutorConfigurationSupport#setAwaitTerminationMillis

    • setRejectTasksWhenLimitReached

      public void setRejectTasksWhenLimitReached(boolean rejectTasksWhenLimitReached)
      Specify whether to reject tasks when the concurrency limit has been reached, throwing TaskRejectedException on any further submission attempts.

      The default is false, blocking the caller until the submission can be accepted. Switch this to true for immediate rejection instead.

      Since:
      6.2.6

    • setConcurrencyLimit

      public void setConcurrencyLimit(int concurrencyLimit)
      Set the maximum number of parallel task executions allowed. The default of -1 indicates no concurrency limit at all.

      This is the equivalent of a maximum pool size in a thread pool, preventing temporary overload of the thread management system. However, in contrast to a thread pool with a managed task queue, this executor will block the submitter until the task can be accepted when the configured concurrency limit has been reached. If you prefer queue-based task hand-offs without such blocking, consider using a ThreadPoolTaskExecutor instead.

      See Also:

    • getConcurrencyLimit

      public final int getConcurrencyLimit()
      Return the maximum number of parallel task executions allowed.

    • isThrottleActive

      public final boolean isThrottleActive()
      Return whether the concurrency throttle is currently active.
      Returns:
      true if the concurrency limit for this instance is active
      See Also:

    • isActive

      public boolean isActive()
      Return whether this executor is still active, i.e. not closed yet, and therefore accepts further task submissions. Otherwise, it is either in the task termination phase or entirely shut down already.
      Since:
      6.1
      See Also:

    • execute

      public void execute(Runnable task)
      Executes the given task, within a concurrency throttle if configured (through the superclass's settings).
      Specified by:
      execute in interface Executor
      Specified by:
      execute in interface TaskExecutor
      Parameters:
      task - the Runnable to execute (never null)
      See Also:

    • execute

      @Deprecated public void execute(Runnable task, long startTimeout)
      Deprecated.
      Executes the given task, within a concurrency throttle if configured (through the superclass's settings).

      Executes urgent tasks (with 'immediate' timeout) directly, bypassing the concurrency throttle (if active). All other tasks are subject to throttling.

      Specified by:
      execute in interface AsyncTaskExecutor
      Parameters:
      task - the Runnable to execute (never null)
      startTimeout - the time duration (milliseconds) within which the task is supposed to start. This is intended as a hint to the executor, allowing for preferred handling of immediate tasks. Typical values are AsyncTaskExecutor.TIMEOUT_IMMEDIATE or AsyncTaskExecutor.TIMEOUT_INDEFINITE (the default as used by TaskExecutor.execute(Runnable)).
      See Also:

    • submit

      public Future<?> submit(Runnable task)
      Description copied from interface: AsyncTaskExecutor
      Submit a Runnable task for execution, receiving a Future representing that task. The Future will return a null result upon completion.

      As of 6.1, this method comes with a default implementation that delegates to TaskExecutor.execute(Runnable).

      Specified by:
      submit in interface AsyncTaskExecutor
      Parameters:
      task - the Runnable to execute (never null)
      Returns:
      a Future representing pending completion of the task

    • submit

      public <T> Future<T> submit(Callable<T> task)
      Description copied from interface: AsyncTaskExecutor
      Submit a Callable task for execution, receiving a Future representing that task. The Future will return the Callable's result upon completion.

      As of 6.1, this method comes with a default implementation that delegates to TaskExecutor.execute(Runnable).

      Specified by:
      submit in interface AsyncTaskExecutor
      Parameters:
      task - the Callable to execute (never null)
      Returns:
      a Future representing pending completion of the task

    • submitListenable

      public ListenableFuture<?> submitListenable(Runnable task)
      Description copied from interface: AsyncListenableTaskExecutor
      Submit a Runnable task for execution, receiving a ListenableFuture representing that task. The Future will return a null result upon completion.
      Specified by:
      submitListenable in interface AsyncListenableTaskExecutor
      Parameters:
      task - the Runnable to execute (never null)
      Returns:
      a ListenableFuture representing pending completion of the task

    • submitListenable

      public <T> ListenableFuture<T> submitListenable(Callable<T> task)
      Description copied from interface: AsyncListenableTaskExecutor
      Submit a Callable task for execution, receiving a ListenableFuture representing that task. The Future will return the Callable's result upon completion.
      Specified by:
      submitListenable in interface AsyncListenableTaskExecutor
      Parameters:
      task - the Callable to execute (never null)
      Returns:
      a ListenableFuture representing pending completion of the task

    • doExecute

      protected void doExecute(Runnable task)
      Template method for the actual execution of a task.

      The default implementation creates a new Thread and starts it.

      Parameters:
      task - the Runnable to execute
      See Also:

    • newThread

      protected Thread newThread(Runnable task)
      Create a new Thread for the given task.
      Parameters:
      task - the Runnable to create a Thread for
      Returns:
      the new Thread instance
      Since:
      6.1
      See Also:

    • close

      public void close()
      This close methods tracks the termination of active threads if a concrete task termination timeout has been set. Otherwise, it is not necessary to close this executor.
      Specified by:
      close in interface AutoCloseable
      Since:
      6.1