How can I shutdown Spring task executor/scheduler pools before all other beans in the web app are destroyed?

Question

In a Spring web application I have several DAO and service layer beans. One service layer bean has annotated @Async / @Scheduled methods. These methods depend on other (auto

Answer 1

I have added below code to terminate tasks you can use it. You may change the retry numbers.

package com.xxx.test.schedulers;

import java.util.Map;
import java.util.concurrent.TimeUnit;

import org.apache.log4j.Logger;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextClosedEvent;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.stereotype.Component;

import com.xxx.core.XProvLogger;

@Component
class ContextClosedHandler implements ApplicationListener<ContextClosedEvent> , ApplicationContextAware,BeanPostProcessor{


private ApplicationContext context;

public Logger logger = XProvLogger.getInstance().x;

public void onApplicationEvent(ContextClosedEvent event) {


    Map<String, ThreadPoolTaskScheduler> schedulers = context.getBeansOfType(ThreadPoolTaskScheduler.class);

    for (ThreadPoolTaskScheduler scheduler : schedulers.values()) {         
        scheduler.getScheduledExecutor().shutdown();
        try {
            scheduler.getScheduledExecutor().awaitTermination(20000, TimeUnit.MILLISECONDS);
            if(scheduler.getScheduledExecutor().isTerminated() || scheduler.getScheduledExecutor().isShutdown())
                logger.info("Scheduler "+scheduler.getThreadNamePrefix() + " has stoped");
            else{
                logger.info("Scheduler "+scheduler.getThreadNamePrefix() + " has not stoped normally and will be shut down immediately");
                scheduler.getScheduledExecutor().shutdownNow();
                logger.info("Scheduler "+scheduler.getThreadNamePrefix() + " has shut down immediately");
            }
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    Map<String, ThreadPoolTaskExecutor> executers = context.getBeansOfType(ThreadPoolTaskExecutor.class);

    for (ThreadPoolTaskExecutor executor: executers.values()) {
        int retryCount = 0;
        while(executor.getActiveCount()>0 && ++retryCount<51){
            try {
                logger.info("Executer "+executor.getThreadNamePrefix()+" is still working with active " + executor.getActiveCount()+" work. Retry count is "+retryCount);
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        if(!(retryCount<51))
            logger.info("Executer "+executor.getThreadNamePrefix()+" is still working.Since Retry count exceeded max value "+retryCount+", will be killed immediately");
        executor.shutdown();
        logger.info("Executer "+executor.getThreadNamePrefix()+" with active " + executor.getActiveCount()+" work has killed");
    }
}


@Override
public void setApplicationContext(ApplicationContext context)
        throws BeansException {
    this.context = context;

}


@Override
public Object postProcessAfterInitialization(Object object, String arg1)
        throws BeansException {
    return object;
}


@Override
public Object postProcessBeforeInitialization(Object object, String arg1)
        throws BeansException {
    if(object instanceof ThreadPoolTaskScheduler)
        ((ThreadPoolTaskScheduler)object).setWaitForTasksToCompleteOnShutdown(true);
    if(object instanceof ThreadPoolTaskExecutor)
        ((ThreadPoolTaskExecutor)object).setWaitForTasksToCompleteOnShutdown(true);
    return object;
}

}

Answer 2

Two ways:

1. Have a bean implement ApplicationListener<ContextClosedEvent>. onApplicationEvent() will get called before the context and all the beans are destroyed.

2. Have a bean implement Lifecycle or SmartLifecycle. stop() will get called before the context and all the beans are destroyed.

Either way you can shut down the task stuff before the bean destroying mechanism takes place.

Eg:

@Component
public class ContextClosedHandler implements ApplicationListener<ContextClosedEvent> {
    @Autowired ThreadPoolTaskExecutor executor;
    @Autowired ThreadPoolTaskScheduler scheduler;

    @Override
    public void onApplicationEvent(ContextClosedEvent event) {
        scheduler.shutdown();
        executor.shutdown();
    }       
}

(Edit: Fixed method signature)

Answer 3

We can add "AwaitTerminationSeconds" property for both taskExecutor and taskScheduler as below,

<property name="awaitTerminationSeconds" value="${taskExecutor .awaitTerminationSeconds}" />

<property name="awaitTerminationSeconds" value="${taskScheduler .awaitTerminationSeconds}" />

Documentation for "waitForTasksToCompleteOnShutdown" property says, when shutdown is called

"Spring's container shutdown continues while ongoing tasks are being completed. If you want this executor to block and wait for the termination of tasks before the rest of the container continues to shut down - e.g. in order to keep up other resources that your tasks may need -, set the "awaitTerminationSeconds" property instead of or in addition to this property."

https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/scheduling/concurrent/ExecutorConfigurationSupport.html#setWaitForTasksToCompleteOnShutdown-boolean-

So it is always advised to use waitForTasksToCompleteOnShutdown and awaitTerminationSeconds properties together. Value of awaitTerminationSeconds depends on our application.

Answer 4

I had similar issues with the threads being started in Spring bean. These threads were not closing properly after i called executor.shutdownNow() in @PreDestroy method. So the solution for me was to let the thread finsih with IO already started and start no more IO, once @PreDestroy was called. And here is the @PreDestroy method. For my application the wait for 1 second was acceptable.

@PreDestroy
    public void beandestroy() {
        this.stopThread = true;
        if(executorService != null){
            try {
                // wait 1 second for closing all threads
                executorService.awaitTermination(1, TimeUnit.SECONDS);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }
    }

Here I have explained all the issues faced while trying to close threads.http://programtalk.com/java/executorservice-not-shutting-down/

Answer 5

If it is going to be a web based application, you can also use the ServletContextListener interface.

public class SLF4JBridgeListener implements ServletContextListener {

   @Autowired 
   ThreadPoolTaskExecutor executor;

   @Autowired 
   ThreadPoolTaskScheduler scheduler;

    @Override
    public void contextInitialized(ServletContextEvent sce) {

    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
         scheduler.shutdown();
         executor.shutdown();     

    }

}