[Vertx] VertxOptions - Thread pool 개수 설정

@ 방법

VertxOption vert_option = new VertxOptions().setClusterd(true);

vert_option.setWorkerPoolSize(100);

참고) default_worker_pool_size는 20개

DEFAULT_WORKER_POOL_SIZE The default number of threads in the worker pool = 20

참고사이트

https://vertx.io/docs/apidocs/io/vertx/core/VertxOptions.html