Shutting down TaskScheduler does not stop running #Scheduled method - spring

Question

I have a class with a method annotated #Scheduled
#Component
#Slf4j
public class MyScheduler {
#Scheduled(cron = "${polling-job-cron}") //each minute
public void pollingJob() {
log.info("starting polling job...");
//some work
log.info("polling job finished.");
}
}
and a configuration for taskScheduler:
#Bean
public ThreadPoolTaskScheduler taskScheduler() {
ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
scheduler.setPoolSize(5);
scheduler.setThreadNamePrefix("mynameofscheduler");
scheduler.setWaitForTasksToCompleteOnShutdown(true);
scheduler.setAwaitTerminationSeconds(30);
scheduler.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
return scheduler;
}
I'm trying to use graceful shutdown by using class which waits for ContextClosedEvent :
#Component
#Slf4j
public class GracefulShutdown implements ApplicationListener<ContextClosedEvent> {
private final ApplicationContext context;
private final ThreadPoolTaskScheduler taskScheduler;
public GracefulShutdown(ApplicationContext context,
ThreadPoolTaskScheduler taskScheduler) {
this.context = context;
this.taskScheduler = taskScheduler;
}
#Override
public void onApplicationEvent(ContextClosedEvent event) {
log.info("Graceful shutdown - start");
log.info("Closing task scheduler");
taskScheduler.shutdown(); //1
taskScheduler.getScheduledThreadPoolExecutor().shutdown(); //2
log.error("Closed task scheduler");
//give k8s a chance to hit in readinessProbe and stop sending requests to this pod
try {
Thread.sleep(80000); //3
} catch (InterruptedException error) {
log.info("error while trying to sleep");
error.printStackTrace();
}
log.info("Closing spring context with startup date, {}, parent: {}, id: {}, name: {}",
context.getStartupDate(), context.getParent(), context.getId(), context.getDisplayName());
((ConfigurableApplicationContext) context).close();
log.info("Graceful shutdown - end");
}
and even though I'm closing taskScheduler and underlying taskExecutor new tasks are still ran by #Scheduled. Code of GracefulShutdown is ran when SIGTERM is send, and other that closing taskScheduler it works fine.
Graceful shutdown - start
Closing task scheduler
Closed task scheduler
starting polling job...
polling job finished
starting polling job...
polling job finished.
threadPoolPrefix is logged in front of those lines (I've cut that above as line were too long to read):
{"timeMillis":1534234560001,"thread":"mynameofscheduler","level":"INFO","loggerName":"myclassr","message":"starting polling job..."
I thought that maybe some other taskScheduler is used and I'm shutting down wrong one, but its all mynameofscheduler which is configured in #Bean

Answer 1

thx to M. Deinum. I was messing up with spring shutting down flow. I've fixed that by registering shutdown hook:
public static void main(String[] args) {
ConfigurableApplicationContext context = SpringApplication.run(AgileStreamApplication.class, args);
Runtime.getRuntime().addShutdownHook(new Thread(new GracefulShutdownHook(context)));
}
and now I don't have to shut down taskSchedulers explicitly. It's done by spring.

Answer 2

Because by default the ScheduledThreadPoolExecutor will wait for all delayed scheduled tasks to finish executing, even if scheduled tasks aren't running at that time.
Try this below:
#Bean
public ThreadPoolTaskScheduler taskScheduler() {
ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler() {
private static final long serialVersionUID = -1L;
#Override
public void destroy() {
this.getScheduledThreadPoolExecutor().setExecuteExistingDelayedTasksAfterShutdownPolicy(false);
super.destroy();
}
};
scheduler.setPoolSize(5);
scheduler.setThreadNamePrefix("mynameofscheduler");
scheduler.setWaitForTasksToCompleteOnShutdown(true);
scheduler.setAwaitTerminationSeconds(30);
scheduler.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
return scheduler;
}
Then the ScheduledThreadPoolExecutor will only wait for scheduled tasks which are currently running to finish executing.