Spring Task schedu

Question

I'm using the Spring task executor system for the first time and just cannot get it to work...

I've read the various posts on SO already about this but can get no indication that the task is being executed. First of all I tried @Scheduled annotations on my service beans but after reading that this encountered problems with AOP proxies I'm using straight XML configuration as so:

<task:executor id="executorWithPoolSizeRange"
        pool-size="5-25"
        queue-capacity="100" />       
 <task:scheduler id="taskScheduler" pool-size="2" /> 
 <task:scheduled-tasks>
 <task:scheduled ref="fileWriter" method="test" fixed-rate="5000" />
</task:scheduled-tasks>

With fileWriter bean being a regular Spring bean with the test method as so:

public void test (){
   System.err.println("run in job");
}

From running with DEBUG logging settings I know the following:

1. The beans are loaded and initialised.
2. If I mistype the name of the 'method' attribute, an exception is thrown, so the task definition is at least parsed.
3. There is nothing in the debug statements indicating any activation of the task
4. A breakpoint in the test method is never triggered.

I'm expecting to see that every 5 seconds while either my app or spring unit tests are running, to see the message from the test() method printed out on the console. I'm using Spring 3.0.6 and testing the app running through Jetty in Eclipse 3.7 on Mac 10.6 Java 6. All other Spring features we use (database, security, MVC work fine). Would be really grateful for any suggestions!

Answer 1

If you haven't try adding Quartz to your classpath (you shouldn't need it but...).

Whats most likely happening is that the scheduler is running and failing to execute your proxy. The proxy probably throws an exception and the scheduler's exception policy is probably discarding it.

The other option... (and I am probably going to get down voted) is to not use Springs scheduler. Unless you need the Quartz Cron stuff I find Springs Task scheduler overly complicated and yet weak compared to:

Guava's ListeningScheduledExecutorService

The listening executor service will allow you to chain events. You can easily wrap the above in some service bean. Yes I know you probably want the decoupling that Spring provides... but you can get far better decoupling and event based by combing the ExecutorService and Guava's EventBus.

Answer 2

Try this:

 <task:scheduled-tasks scheduler="taskScheduler">
   <task:scheduled ref="fileWriter" method="test" fixed-rate="5000" />
 </task:scheduled-tasks>