Class ThreadPoolExecutorFactoryBean

All Implemented Interfaces:
Serializable, ThreadFactory, Aware, BeanNameAware, DisposableBean, FactoryBean<ExecutorService>, InitializingBean

public class ThreadPoolExecutorFactoryBean extends ExecutorConfigurationSupport implements FactoryBean<ExecutorService>
JavaBean that allows for configuring a ThreadPoolExecutor in bean style (through its "corePoolSize", "maxPoolSize", "keepAliveSeconds", "queueCapacity" properties) and exposing it as a bean reference of its native ExecutorService type.

The default configuration is a core pool size of 1, with unlimited max pool size and unlimited queue capacity. This is roughly equivalent to Executors.newSingleThreadExecutor(), sharing a single thread for all tasks. Setting "queueCapacity" to 0 mimics Executors.newCachedThreadPool(), with immediate scaling of threads in the pool to a potentially very high number. Consider also setting a "maxPoolSize" at that point, as well as possibly a higher "corePoolSize" (see also the "allowCoreThreadTimeOut" mode of scaling).

For an alternative, you may set up a ThreadPoolExecutor instance directly using constructor injection, or use a factory method definition that points to the Executors class. This is strongly recommended in particular for common @Bean methods in configuration classes, where this FactoryBean variant would force you to return the FactoryBean type instead of the actual Executor type.

If you need a timing-based ScheduledExecutorService instead, consider ScheduledExecutorFactoryBean.

Juergen Hoeller
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  • Constructor Details

    • ThreadPoolExecutorFactoryBean

      public ThreadPoolExecutorFactoryBean()
  • Method Details

    • setCorePoolSize

      public void setCorePoolSize(int corePoolSize)
      Set the ThreadPoolExecutor's core pool size. Default is 1.
    • setMaxPoolSize

      public void setMaxPoolSize(int maxPoolSize)
      Set the ThreadPoolExecutor's maximum pool size. Default is Integer.MAX_VALUE.
    • setKeepAliveSeconds

      public void setKeepAliveSeconds(int keepAliveSeconds)
      Set the ThreadPoolExecutor's keep-alive seconds. Default is 60.
    • setAllowCoreThreadTimeOut

      public void setAllowCoreThreadTimeOut(boolean allowCoreThreadTimeOut)
      Specify whether to allow core threads to time out. This enables dynamic growing and shrinking even in combination with a non-zero queue (since the max pool size will only grow once the queue is full).

      Default is "false".

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    • setPrestartAllCoreThreads

      public void setPrestartAllCoreThreads(boolean prestartAllCoreThreads)
      Specify whether to start all core threads, causing them to idly wait for work.

      Default is "false".

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    • setQueueCapacity

      public void setQueueCapacity(int queueCapacity)
      Set the capacity for the ThreadPoolExecutor's BlockingQueue. Default is Integer.MAX_VALUE.

      Any positive value will lead to a LinkedBlockingQueue instance; any other value will lead to a SynchronousQueue instance.

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    • setExposeUnconfigurableExecutor

      public void setExposeUnconfigurableExecutor(boolean exposeUnconfigurableExecutor)
      Specify whether this FactoryBean should expose an unconfigurable decorator for the created executor.

      Default is "false", exposing the raw executor as bean reference. Switch this flag to "true" to strictly prevent clients from modifying the executor's configuration.

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    • initializeExecutor

      protected ExecutorService initializeExecutor(ThreadFactory threadFactory, RejectedExecutionHandler rejectedExecutionHandler)
      Description copied from class: ExecutorConfigurationSupport
      Create the target ExecutorService instance. Called by afterPropertiesSet.
      Specified by:
      initializeExecutor in class ExecutorConfigurationSupport
      threadFactory - the ThreadFactory to use
      rejectedExecutionHandler - the RejectedExecutionHandler to use
      a new ExecutorService instance
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    • createExecutor

      protected ThreadPoolExecutor createExecutor(int corePoolSize, int maxPoolSize, int keepAliveSeconds, BlockingQueue<Runnable> queue, ThreadFactory threadFactory, RejectedExecutionHandler rejectedExecutionHandler)
      Create a new instance of ThreadPoolExecutor or a subclass thereof.

      The default implementation creates a standard ThreadPoolExecutor. Can be overridden to provide custom ThreadPoolExecutor subclasses.

      corePoolSize - the specified core pool size
      maxPoolSize - the specified maximum pool size
      keepAliveSeconds - the specified keep-alive time in seconds
      queue - the BlockingQueue to use
      threadFactory - the ThreadFactory to use
      rejectedExecutionHandler - the RejectedExecutionHandler to use
      a new ThreadPoolExecutor instance
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    • createQueue

      protected BlockingQueue<Runnable> createQueue(int queueCapacity)
      Create the BlockingQueue to use for the ThreadPoolExecutor.

      A LinkedBlockingQueue instance will be created for a positive capacity value; a SynchronousQueue else.

      queueCapacity - the specified queue capacity
      the BlockingQueue instance
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    • getObject

      @Nullable public ExecutorService getObject()
      Description copied from interface: FactoryBean
      Return an instance (possibly shared or independent) of the object managed by this factory.

      As with a BeanFactory, this allows support for both the Singleton and Prototype design pattern.

      If this FactoryBean is not fully initialized yet at the time of the call (for example because it is involved in a circular reference), throw a corresponding FactoryBeanNotInitializedException.

      As of Spring 2.0, FactoryBeans are allowed to return null objects. The factory will consider this as normal value to be used; it will not throw a FactoryBeanNotInitializedException in this case anymore. FactoryBean implementations are encouraged to throw FactoryBeanNotInitializedException themselves now, as appropriate.

      Specified by:
      getObject in interface FactoryBean<ExecutorService>
      an instance of the bean (can be null)
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    • getObjectType

      public Class<? extends ExecutorService> getObjectType()
      Description copied from interface: FactoryBean
      Return the type of object that this FactoryBean creates, or null if not known in advance.

      This allows one to check for specific types of beans without instantiating objects, for example on autowiring.

      In the case of implementations that are creating a singleton object, this method should try to avoid singleton creation as far as possible; it should rather estimate the type in advance. For prototypes, returning a meaningful type here is advisable too.

      This method can be called before this FactoryBean has been fully initialized. It must not rely on state created during initialization; of course, it can still use such state if available.

      NOTE: Autowiring will simply ignore FactoryBeans that return null here. Therefore it is highly recommended to implement this method properly, using the current state of the FactoryBean.

      Specified by:
      getObjectType in interface FactoryBean<ExecutorService>
      the type of object that this FactoryBean creates, or null if not known at the time of the call
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    • isSingleton

      public boolean isSingleton()
      Description copied from interface: FactoryBean
      Is the object managed by this factory a singleton? That is, will FactoryBean.getObject() always return the same object (a reference that can be cached)?

      NOTE: If a FactoryBean indicates to hold a singleton object, the object returned from getObject() might get cached by the owning BeanFactory. Hence, do not return true unless the FactoryBean always exposes the same reference.

      The singleton status of the FactoryBean itself will generally be provided by the owning BeanFactory; usually, it has to be defined as singleton there.

      NOTE: This method returning false does not necessarily indicate that returned objects are independent instances. An implementation of the extended SmartFactoryBean interface may explicitly indicate independent instances through its SmartFactoryBean.isPrototype() method. Plain FactoryBean implementations which do not implement this extended interface are simply assumed to always return independent instances if the isSingleton() implementation returns false.

      The default implementation returns true, since a FactoryBean typically manages a singleton instance.

      Specified by:
      isSingleton in interface FactoryBean<ExecutorService>
      whether the exposed object is a singleton
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