Vert.x EventLoop Thread used on JAX-RS methods with Undertow

[bcluap]

Describe the bug
The second HTTP request to an JAX-RS endpoint after doing a live reload results in the vert.x eventloop thread pool being used for all subsequent requests on the JAX-RS endpoint.

Expected behavior
The worker thread pool should always be used

Actual behavior
The thread pool changes to the eventloop pool after a live reload

To Reproduce
Steps to reproduce the behavior:
git clone https://github.com/bcluap/quarkus.git
cd quarkus/getting-started/
mvn quarkus:dev

Then:
curl http://localhost:8080/test --> uses executor

Then:
Make a change to the Test.java file and save it

Then:
curl http://localhost:8080/test --> uses executor
curl http://localhost:8080/test --> uses eventloop

Configuration

Empty application.properties

I can only reproduce this when the undertow servlet extension is in the project

Screenshots

Environment (please complete the following information):
java -version
openjdk version "11.0.5" 2019-10-15
OpenJDK Runtime Environment (build 11.0.5+10-post-Ubuntu-0ubuntu1.118.04)
OpenJDK 64-Bit Server VM (build 11.0.5+10-post-Ubuntu-0ubuntu1.118.04, mixed mode, sharing)
paul@PCBLaptop:/Source/quarkus/getting-started$ uname -a
Linux PCBLaptop 4.15.0-74-generic #84-Ubuntu SMP Thu Dec 19 08:06:28 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

Additional context
Cannot reproduce without undertow

[gsmet]

/cc @stuartwdouglas @FroMage

[gsmet]

@bcluap a bit unrelated but there's a message bootstrap classpath not set in conjunction with.... What's that? It doesn't look like expected either or is it?

[bcluap]

Thats just an issue in the POM. Fixed that but same bug still presents itself

[FroMage]

Yeah, I can reproduce. It alternates between worker and io thread, when I keep hitting the service.

[FroMage]

This doesn't happen when not using undertow.