How to use virtual threads with @Asynchronous @Inject ExecutorService executorService with Quarkus on JDK21?

[dhoffer]

I would like to use virtual threads for blocking and/or I/O related operations where pre JDK virtual threads were platform threads. How can I configure Quarkus to use virtual threads for the following cases:

`@Asynchronous

@Inject
ExecutorService executorService`

[quarkus-bot[bot]]

/cc @cescoffier (virtual-threads), @ozangunalp (virtual-threads)

[ozangunalp]

Where does the @Asynchronous annotation come from? (It doesn't look like MP Fault-Tolerance annotation)

If you are looking to schedule tasks on VTs you can inject the virtual threads executor service

[mschorsch]

@ozangunalp

Where does the @asynchronous annotation come from? (It doesn't look like MP Fault-Tolerance annotation)

https://jakarta.ee/specifications/platform/10/apidocs/jakarta/enterprise/concurrent/asynchronous

@dhoffer I don't think Quarkus supports @Asynchronous but you can inject a managed executor see https://quarkus.io/guides/context-propagation#usage-example-for-completionstage.

For Virtual Thread support see

• https://quarkus.io/guides/virtual-threads
• https://quarkus.io/blog/virtual-thread-1/

[dhoffer]

Bummer regarding @asynchronous, but regarding @VirtualThreads will it fall back to platform threads if not available? E.g. not JDK21 or later.

[cescoffier]

Yes, the executor does that.

[Ladicek]

That is correct, SmallRye Fault Tolerance as integrated into Quarkus offloads all blocking @Asynchronous method calls to the Quarkus main thread pool.

(Note that this @Asynchronous annotation comes from MicroProfile Fault Tolerance. To the best of my knowledge, Quarkus doesn't support Jakarta Concurrency at all.)

[dhoffer]

@Ladicek That is unfortunate. Quarkus does support VT for at least REST serevices and for Executors it's a shame that Quarkus is not consistant and always support VT where it makes sense and @asynchronous is definately where VT support makes sense.

[cescoffier]

IT would only make sense if you combine @asynchronous and @RunOnVirtualThreads, otherwise it would be very dangerous.

[dhoffer]

Yes I was thinking the same thing, combine @asynchronous <https://github.com/asynchronous> and @RunOnVirtualThreads no need for something new/different. To me this is a required feature of Quarkus as why should one part/feature only use platform threads?

…

-David

On Mon, Sep 2, 2024 at 11:34 PM Clement Escoffier ***@***.***> wrote: IT would only make sense if you combine @asynchronous <https://github.com/asynchronous> and @RunOnVirtualThreads, otherwise it would be very dangerous. — Reply to this email directly, view it on GitHub <#42448 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAL7BL6PLOBCDDLJWZ76ZX3ZUVC6ZAVCNFSM6AAAAABMIN7YWOVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTANJSG42DEMA> . You are receiving this because you were mentioned.Message ID: ***@***.***>