How to inject Quarkus managed ExecutorService and ScheduledExecutorService?

[nimo23]

In Wildfly I can inject the Executor services managed by Wildfly as follows:

// cast from ManagedExecutorService to ExecutorService
@Resource(lookup = "java:jboss/ee/concurrency/executor/default")
private ExecutorService executor;

// cast from ManagedScheduledExecutorService to ScheduledExecutorService
@Resource(lookup = "java:jboss/ee/concurrency/scheduler/default")
private ScheduledExecutorService scheduler;

How can I access/inject the Quarkus managed ExecutorService and ScheduledExecutorService?

[quarkus-bot[bot]]

/cc @manovotn (scheduler), @mkouba (scheduler)

[manovotn]

You can inject a managed executor:

import org.eclipse.microprofile.context.ManagedExecutor;

// ...

@Inject
ManagedExecutor exec;

The above is a basic version. You can modify it too in terms of queue, max async tasks and what contexta should it propagate.

As for scheduled tasks, I'd suggest looking at quarkus-scheduler which might be what you ultimately want to achieve?
See https://quarkus.io/guides/scheduler-reference

[nimo23]

Would this also be possible?:

@Inject // from Arc directly
private ExecutorService executor;

@Inject // from Arc directly
private ScheduledExecutorService scheduler;

I need these 2 instances. Since I only have ManagedExecutor (as you suggested), I have to cast it to ExecutorService for my class, and I'm still missing a quarkus managed ScheduledExecutorService.

According to https://quarkus.io/guides/virtual-threads, an quarkus managed executor service can also be injected as follows:

@Inject
@VirtualThreads
ExecutorService vThreads;

So I assumed that we can do it also that way:

@Inject // from Arc directly
private ExecutorService executor;

@Inject // from Arc directly
private ScheduledExecutorService scheduler;

But I'm not sure if that's okay.

[nimo23]

I tried it with

@Inject // from Arc directly
private ExecutorService executor;

@Inject // from Arc directly
private ScheduledExecutorService scheduler;

and it seems it works. I logged the injected class instances:

2024-03-01 01:27:26,989 INFO  [io.app] (Quarkus Main Thread) executor = class io.quarkus.arc.generator.ScheduledExecutorService_cAsQhMqDYUnGxT4AN4njjudQ50I_Synthetic_ClientProxy
2024-03-01 01:27:26,989 INFO  [io.app] (Quarkus Main Thread) scheduler = class io.quarkus.arc.generator.ScheduledExecutorService_cAsQhMqDYUnGxT4AN4njjudQ50I_Synthetic_ClientProxy

As you can see, the instances for executor and scheduler are the same. Does this mean that Quarkus uses the same instance for both ManagedExecutor and ScheduledExecutorService? It's a bit irritating because in wildfly the executor and the scheduler are two different instances.

[mkouba]

As you can see, the instances for executor and scheduler are the same. Does this mean that Quarkus uses the same instance for both ManagedExecutor and ScheduledExecutorService? It's a bit irritating because in wildfly the executor and the scheduler are two different instances.

@nimo23 Yes, you can @Inject ExecutorService and @Inject ScheduledExecutorService and it's expected that in both cases you get the same instance (or rather a client proxy delegating to the same instance), i.e. the default executor for blocking tasks.

And indeed, the @Inject @VirtualThreads ExecutorService injects an executor to run tasks on virtual threads.

The @Inject ManagedExecutor mentioned by Matej is a specialized executor that allows you to specify various aspects of context propagation (as defined in the MicroProfile Context Propagation).

[mschorsch]

@nimo23 see also https://quarkus.io/guides/context-propagation#usage-example-for-completionstage

[nimo23]

The @Inject ManagedExecutor mentioned by Matej is a specialized executor that allows you to specify various aspects of context propagation (as defined in the MicroProfile Context Propagation).

Using @Inject ManagedExecutor does not return the (managed) ScheduledExecutorService but the ExecutorService:

managedExecutor = class io.smallrye.context.SmallRyeManagedExecutor_N80A159oF8msb0BBZG1sW4wdTGk_Synthetic_ClientProxy

So I must use

@Inject // from Arc directly
private ExecutorService executor;

@Inject // from Arc directly
private ScheduledExecutorService scheduler;

instead of

@Inject ManagedExecutor.