Question

我们有一个Spring Web应用程序，我们正在从Spring 3.2移植到Spring 4.我们的应用程序在Web应用程序启动时将几个子上下文组合成一个运行时上下文。

我们在两个子上下文中使用单独的TaskSchedulers。使用Spring 3.2，这很好用;使用Spring 4时，我们会收到以下消息的异常：

java.lang.IllegalStateException: More than one TaskScheduler and/or ScheduledExecutorService  exist within the context. Remove all but one of the beans; or implement the SchedulingConfigurer interface and call ScheduledTaskRegistrar#setScheduler explicitly within the configureTasks() callback. Found the following beans: [commonScheduler, communicationTaskScheduler]
        at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:289) ~[spring-context-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:72) ~[spring-context-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:98) ~[spring-context-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:333) ~[spring-context-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:776) ~[spring-context-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:485) ~[spring-context-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403) ~[spring-web-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306) ~[spring-web-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106) ~[spring-web-4.0.1.RELEASE.jar:4.0.1.RELEASE]
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4961) ~[catalina.jar:7.0.50]
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5455) ~[catalina.jar:7.0.50]
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ~[catalina.jar:7.0.50]
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) ~[catalina.jar:7.0.50]
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) ~[catalina.jar:7.0.50]
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:634) ~[catalina.jar:7.0.50]
        at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1074) ~[catalina.jar:7.0.26]
        at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1858) ~[catalina.jar:7.0.26]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) ~[na:1.7.0_25]
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) ~[na:1.7.0_25]
        at java.util.concurrent.FutureTask.run(FutureTask.java:166) ~[na:1.7.0_25]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) ~[na:1.7.0_25]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) ~[na:1.7.0_25]
        at java.lang.Thread.run(Thread.java:724) ~[na:1.7.0_25]

通过以下方式定义一个调度程序：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:task="http://www.springframework.org/schema/task"
    xsi:schemaLocation="
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.0.xsd">

    <!-- Enables annotation-driven task scheduling; detects @Scheduled- and 
        @Async-annotated process methods to be invoked via proxy -->
    <task:annotation-driven mode="aspectj" />
    <task:scheduler id="commonScheduler" pool-size="5" />

</beans>

定义了另一个调度程序（为清楚起见，删除了其他bean）：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd">

    <context:spring-configured />

    <bean id="communicationExecutor"
        class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor">
        <property name="corePoolSize" value="15" />
        <property name="maxPoolSize" value="20" />
        <property name="queueCapacity" value="20" />
    </bean>
    <bean id="communicationTaskScheduler"
        class="org.springframework.scheduling.concurrent.ConcurrentTaskScheduler">
        <property name="concurrentExecutor" ref="communicationExecutor" />
    </bean>

</beans>

在运行时使用（为清晰起见而删除了其他上下文）汇总了上下文：

<beans xmlns="http://www.springframework.org/schema/beans"  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-4.0.xsd">

    <import resource="classpath:spring/tasks-context.xml" />
    <import resource="classpath:spring/collectors-context.xml" />
</beans>

为什么Spring 4有这个限制？应该如何解决它？

Answer 1

是的，这肯定会改变行为。看起来ScheduledAnnotationBeanPostProcessor现在每个上下文限制为2个调度程序。我使用Spring 4的新WebSocket消息代理遇到了这个问题，因为它为Simple STOMP代理和SockJS适配器分配了2个调度程序。当我添加自己的时候，它完全沉浸在你得到的同样的信息中。我发现相当恼人的是我必须通过错误而不是文档找出这个限制。这个问题似乎没有在Spring 4文档中描述过。

解决方案是创建自己的SchedulingConfigurer来管理自己的TaskScheduler。我怀疑原因是只有一个，并且需要添加额外的TaskScheduler实现以便将它们彼此隔离。我做了类似的事情：

@Configuration
@EnableScheduling
public class MySchedulingConfigurer implements SchedulingConfigurer
{
   @Bean
   public TimedThingy timedThingy()
   {
      return new TimedThingy();
   }

  @Bean()
  public ThreadPoolTaskScheduler taskScheduler() {
     return new ThreadPoolTaskScheduler();
  }

  @Override
  public void configureTasks(ScheduledTaskRegistrar taskRegistrar)
  {
      taskRegistrar.setTaskScheduler(taskScheduler());
      taskRegistrar.addFixedRateTask(new Runnable()
      {
         public void run()
         {
            timedThingy().sendIt();
         }
      }, 1000);
  }
}

一旦我这样做了，问题就会消失，事情会按照预期发挥作用。不好的一面是你不能使用@Scheduled之类的注释等等。但是你确实获得了更多的控制权和事情。希望这会有所帮助。

Answer 2

您需要明确指定要与@Scheduled注释一起使用的调度程序。只需添加scheduler属性：

即可

<task:annotation-driven scheduler="commonScheduler" mode="aspectj" />
<task:scheduler id="commonScheduler" pool-size="5" />

Answer 3

只需将bean添加到您的配置中：

 @Bean()
 public ThreadPoolTaskScheduler taskScheduler() {
    return new ThreadPoolTaskScheduler();
 }

为什么Spring 4只允许在上下文中使用一个TaskScheduler？

3 个答案: