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I am current developing an application based on Spring-Boot.

I know that annotation like @Scheduled can schedule tasks. Since users in my application wanna send mails at different time and send only once.

I have already read the post Spring scheduling task - run only once, but it is weird always "new" an localExecutor in a Spring based application.

In that way , once a user schedule sending an email, I have to "new" an localExecutor for his task.

So , are there any better ways?

Community
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Exia
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  • For more dynamic use cases checkout https://stackoverflow.com/questions/46974272/spring-boot-add-new-schedule-job-dynamically – RoBeaToZ Feb 12 '20 at 10:32

5 Answers5

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The simplest way to schedule tasks in Spring is to create method annotated by @Scheduled in spring managed bean. It also required @EnableScheduling in any @Configuration classes.

Spring tutorial

Александр Косарев
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    yes , I have already use this kind of annotations for scheduling task. But in my condition , a user only want to send his mail once at a given time. So if I use the @Schedule annotation , I have to “polling” check whether an mail should be send each several minutes or hours..... – Exia Jan 28 '16 at 15:01
  • Hope [this](http://stackoverflow.com/questions/17402112/correct-way-to-persist-quartz-triggers-in-database) can be helpful for you – Александр Косарев Jan 28 '16 at 15:19
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    Does this works smooth when you have multiple instances of one service in production? – virsha Aug 26 '18 at 11:03
  • Checkout use of [shedlock](https://www.baeldung.com/shedlock-spring) with spring for making this work better in clustered environments (multiple instances) – solecoder Dec 08 '20 at 12:40
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You can use crontab inside @Scheduled 

 private AtomicInteger counter = new AtomicInteger(0);

@Scheduled(cron = "*/2 * * * * *")
public void cronJob() {
    int jobId = counter.incrementAndGet();
    System.out.println("Job " + new Date() + ", jobId: " + jobId);
}
Satish Kr
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you should use quartz-scheduler and send mails at different time and send only once.- put this as a business logic in your code. Please see for spring boot -quartz integration https://github.com/davidkiss/spring-boot-quartz-demo

Pankaj Pandey
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Spring @Scheduled annotation will execute multiple times if you have more than one instance of your app where you have @Scheduled annotation.

If you are using PCF, you can use PCF scheduler https://docs.pivotal.io/scheduler/1-2/using-jobs.html to avoid this issue. Using Tasks can solve this issue.

Ketan
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0

I have implemented a 'cron job' system using Quartz Scheduler and Spring Boot Scheduler.

The system supports scheduling based on start and end dates.

  1. It supports scheduling based on daily, weekday, monthly, and weekly frequencies.
  2. It supports running on multiple application instances, but only runs on one
  3. server at a time.
  4. It generates cron expressions dynamically.
  5. It supports scheduling based on time zone.
  6. It is built on Java 8.
  7. And more.

Let me know if anyone needs it, and I will provide the package format

Ashwath naidu
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