java reactor parallel execution by key

parallel_execution_by_key.java

import java.util.Arrays;
import reactor.core.publisher.Flux;
import reactor.core.scheduler.Schedulers;

Flux.fromIterable(Arrays.asList(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20))
        .groupBy(x -> x.hashCode() % 5)
        .parallel(10)
        .runOn(Schedulers.parallel())
        .flatMap(g -> g.collectMap(y -> {log.info(" g: "+g.key()+" y: "+ y); return y;}).log("subscr"))
        .subscribe();