Configure the Grails event bus scheduler for RxJava 2.x

We are using Grails 4.x with RxJava 2.x plugin (grails-event-rxjava2:4.0.0). We are trying to change the default Io scheduler to a different one. Documentation shows how to this for the default event bus implementation, but we cannot change it for RxJava 2

grails-app/conf/spring/resources.groovy

import org.grails.events.bus.*
import java.util.concurrent.*

beans = {
    eventBus(ExecutorEventBus, Executors.newFixedThreadPool(5))
}

For RxJava2 we are supposed to use RxJavaPlugins class, but we don't know how to configure the resources.groovy.

Anyone can help? Thanks in advance

Solution

RxEventBus is configured with Java's ServiceLoader via a src/main/resources/META-INF/services/grails.events.bus.EventBus file, using its default constructor with a Schedulers.io() scheduler. Since the scheduler attribute is final, the only way I imagine you can achieve what you want is to provide your own implementation:

Make grails-events-rxjava2 a compileOnly dependency, otherwise both RxEventBus and YourEventBus will be found, resulting in an error.

Subclass org.grails.events.rxjava2.RxEventBus:

class YourEventBus extends RxEventBus {
    YourEventBus() {
        super(Schedulers.computation()) //or whatever
    }
}