Spring Scheduler doesn't execute for blocking tasks

January 17, 2022

I am running the below scheduler in spring boot. The crontab time is set for every minute to execute the method. And then I try to block the method for 1.5 mins. I observed that, the method doesn’t execute in next minute of the first execution until the loop executes for 1.5 mins.
I thought it works in asynch ways. Now confused! Is spring scheduler a blocking call?

@Override
    @Scheduled(cron = "0 0/1 * * * ?")
    //@SchedulerLock(name = "test")
    public void test()
    {
        System.out.println("test scheduler enters:"+ LocalDateTime.now());
        //LockAssert.assertLocked();
        //System.out.println("now locked\n");
        long st=System.currentTimeMillis();

        while(true)
        {
            long diff=(System.currentTimeMillis()-st)/1000;
            if(diff>90)
            {
                System.out.println("breaking time:"+(System.currentTimeMillis()-st)/1000+", timeNow:"+ LocalDateTime.now());
                break;
            }
        }
        System.out.println("Out of the loop");
    }

>Solution :

As described in spring scheduler docs the taskScheduler runs by default with a single thread.

You can configure multiple threads by e.g (taken from here):

 @Configuration
 @EnableScheduling
 public class AppConfig implements SchedulingConfigurer {

     @Override
     public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
         taskRegistrar.setScheduler(taskExecutor());
     }

     @Bean(destroyMethod="shutdown")
     public Executor taskExecutor() {
         return Executors.newScheduledThreadPool(100);
     }
 }