Steve Chambers Steve Chambers - 1 year ago 97
Java Question

Is it possible to assign @Scheduled with a period representing "never" (in Spring)?

I'm investigating using @Scheduled at a fixed rate where in some configurable circumstances the scheduled job should never be run.

The documentation doesn't mention this but the default values for

respectively. Can these be used to reliably ensure that the scheduled method doesn't fire?

Answer Source

You can not. When you set the fixedDelay attribute to -1 or attempt use @Scheduled without specifying a valid value for any of its attributes, Spring will complain that no attribute is set:

Exactly one of the 'cron', 'fixedDelay(String)', or 'fixedRate(String)' attributes is required

You can verify this behavior by going through the source code of ScheduledAnnotationBeanPostProcessor#processScheduled.

It contains logic like:

boolean processScheduled = false;

// ...

if (fixedRate >= 0) {
    Assert.isTrue(!processedSchedule, errorMessage);
    processedSchedule = true;
    this.registrar.addFixedRateTask(new IntervalTask(runnable, fixedRate, initialDelay));

// ...

Assert.isTrue(processedSchedule, errorMessage);

Take a look at this SO post for some options for conditionally disabling @Scheduled.

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