Spring MVC how to get progress of running async task

Question

I would like to start an asynchronous task from within controller like in following code sniplet from Spring docs.

import org.springframework.core.task.Tas         


        

Answer 1

One solution could be: in your async thread, write to a DB, and have your checking code check the DB table for progress. You get the additional benefit of persisting performance data for later evaluation.

Also, just use the @Async annotation to kick off the asynchronous thread - makes life easier and is a Spring Way To Do It.

Answer 2

Have you looked at the @Async annotation in the Spring reference doc?

First, create a bean for your asynchronous task:

@Service
public class AsyncServiceBean implements ServiceBean {

    private AtomicInteger cn;

    @Async
    public void doSomething() { 
        // triggers the async task, which updates the cn status accordingly
    }

    public Integer getCn() {
        return cn.get();
    }
}

Next, call it from the controller:

@Controller
public class YourController {

    private final ServiceBean bean;

    @Autowired
    YourController(ServiceBean bean) {
        this.bean = bean;
    }

    @RequestMapping(value = "/trigger")
    void triggerAsyncJob() {
        bean.doSomething();
    }

    @RequestMapping(value = "/status")
    @ResponseBody
    Map<String, Integer> fetchStatus() {
        return Collections.singletonMap("cn", bean.getCn());
    }        
}

Remember to configure an executor accordingly, e.g.

<task:annotation-driven executor="myExecutor"/>
<task:executor id="myExecutor" pool-size="5"/>

Answer 3

Check this github source, it gives pretty simple way of catching status of the background job using @Async of Spring mvc.

https://github.com/frenos/spring-mvc-async-progress/tree/master/src/main/java/de/codepotion/examples/asyncExample

Answer 4

Ignoring synchronization issues you could do something like this:

  private class MessagePrinterTask implements Runnable { 
    private int cn; 

    public int getCN() {
      return cn;
    }

    ...
  }


  public class TaskExecutorExample { 
    MessagePrinterTask printerTask;

    public void printMessages() { 
      printerTask = new MessagePrinterTask();
      taskExecutor.execute(printerTask); 
    }
    ...
  }