I have a simple Vertx worker vertical with 4 instances for scaling as defined below. When multiple requests come, I was expecting that each worker instances will process individual request concurrently (4 requests at a time).
Vertx vertx = Vertx.vertx();
DeploymentOptions deploymentOptions = new DeploymentOptions()
.setWorker(true)
.setInstances(4);
vertx.deployVerticle(MailVertical.class.getName(), deploymentOptions);
some code to plumb incoming mail message to publishing method.
// This is executed once per incoming message
this.vertx.eventBus().publish("anAddress", messageString);
Vertical Consumer code to log incoming mail message
public class MailVertical extends AbstractVerticle {
private static final Logger logger = LoggerFactory.getLogger(MailVertical.class);
@Override
public void start(Promise<Void> future) {
logger.info("Welcome to Vertx: MailVertical.");
vertx.eventBus().consumer("anAddress", message -> {
String msg = message.body().toString();
for(int i=0;i<50;i++){
logger.info(msg);
}
try {
updateStatusInDB(msg);
} catch (SQLException e) {
e.printStackTrace();
}
});
}
However, I am observing that each request is processed by all 4 instances somewhat concurrently i.e. if 1 request come in, total 4 processing events occur = 200 log messages.
...
...
[vert.x-worker-thread-7] INFO com.vertx.mailproject.MailVertical - {"msg":"sample message for app-2123x mail notification","appname":"app-1","msgid":"64fd684b-45a8-48c7-9526-4606d6adc311"}
[vert.x-worker-thread-6] INFO com.vertx.mailproject.MailVertical - Msg: sample message for app-2123x mail notification updated to SENT in DB.
[vert.x-worker-thread-7] INFO com.vertx.mailproject.MailVertical - Msg: sample message for app-2123x mail notification updated to SENT in DB.
[vert.x-worker-thread-4] INFO com.vertx.mailproject.MailVertical - Msg: sample message for app-2123x mail notification updated to SENT in DB.
[vert.x-worker-thread-5] INFO com.vertx.mailproject.MailVertical - Msg: sample message for app-2123x mail notification updated to SENT in DB.
Any suggestion what am I doing wrong here? Or is this expected.
vertx-core = 4.2.3
Yes this is indeed a correct behavior. You are starting 4 worker threads and then registering all of them against the same address "anAddress".
Publish Subscribe pattern is being used here. With the method publish() all the registered consumer/handler will receive this event. see Publish / subscribe messaging
If you want only one of worker to receive this event, then use Point-to-point and Request-Response messaging. Basically replace publish() with send()
But looking at your code, I would suggest instead of using worker verticle use executeBlocking in standard verticle