How to make @Schedule method to be called only once at a time

问题

We are using the @Schedule EJB annotation to start a scheduled job do a delta SOLR import every x seconds. Of course we want to have as less timeshift in indexing as possible. Currently I try to do the delta every 5 seconds.

So my question is: Can I make sure the job is only called once? So let's say the indexing is lasting longer than 5 seconds, will the next schedules call wait until the previous is coming back?

回答1:

Yes. You can make the bean a @Singleton and use @Lock(LockType.Write) to make sure that timers don't run in parallel. Note that LockType.Write is the default in a Singleton. So even the explicit mention with the annotation would not be required.

来源：https://stackoverflow.com/questions/8164176/how-to-make-schedule-method-to-be-called-only-once-at-a-time