Quarkus Scheduler & ExecutorService questions

[David Hoffer]

I see Quarkus has a  quarkus-scheduler  module, I have a few questions regarding this.  Currently our app handles this via Java ExecutorService.

1. What are the advantages to using quarkus-scheduler vs. Executors.newXXX()?

2. Currently we can configure these at runtime to be enabled/disabled, is there a way to do that with quarkus-scheduler?  E.g. I know I can create a Scheduler to trigger every 10 seconds but can that be disabled at runtime so that it doesn't trigger or would I have to just configure it to be a noop when triggered if disabled?

3.What about cases where I just need some logic to run in a new thread until the app is shut down, does Quarkus have a substitute for Executors.newSingleThreadExecutor()?

-Dave

[Martin Kouba]

Hi David,

On 16. 09. 21 21:46, David Hoffer wrote:
> I see Quarkus has a quarkus-scheduler  module, I have a few questions
> regarding this.  Currently our app handles this via Java ExecutorService.
>
> 1. What are the advantages to using quarkus-scheduler vs.
> Executors.newXXX()?

a. The declarative @Scheduled methods API
- https://quarkus.io/guides/scheduler-reference#scheduled-methods
b. Quarkus manages the underlying shared executor for you (and it's
configurable)
c. Integrated metrics
- https://quarkus.io/guides/scheduler-reference#metrics
d. Integrated in Dev UI - you can for example trigger the job manually...
e. You can also leverage the same API and functionality together with
the Quartz library: https://quarkus.io/guides/quartz

> 2. Currently we can configure these at runtime to be enabled/disabled,
> is there a way to do that with quarkus-scheduler?  E.g. I know I can
> create a Scheduler to trigger every 10 seconds but can that be disabled
> at runtime so that it doesn't trigger or would I have to just configure
> it to be a noop when triggered if disabled?

I'm not sure I fully understand but you can specify the interval via a
config property, e.g. @Scheduled(every = "${myMethod.every}"), the "off"
and "disabled" values just disable the method, and even disable the
method if no property is defined: @Scheduled(every =
"${myMethod.every:off}"). See also
https://quarkus.io/guides/scheduler-reference#intervals.

Alternatively, you can pause/resume a scheduled method that has a
specific identity, e.g. @Scheduled(identity = "myScheduledMethod"). You
can do so via the injected scheduler:
https://quarkus.io/guides/scheduler-reference#scheduler

> 3.What about cases where I just need some logic to run in a new thread
> until the app is shut down, does Quarkus have a substitute for
> Executors.newSingleThreadExecutor()?

Does it need to be a new thread? In general, you can declare a CDI
observer for the ShutdownEvent:
https://quarkus.io/guides/lifecycle#listening-for-startup-and-shutdown-events

>
> -Dave
>
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--
Martin Kouba
Software Engineer
Red Hat, Czech Republic