Timeout in Vert.x 3.9 WebClient not working as expected - vert.x

Question

I need to set a request timeout on a downstream backend call. However, the WebClient class in Vert.x 3.9 doesn't seem to work as I expected. Here's some test code for it:
package client;
import io.vertx.reactivex.core.AbstractVerticle;
import io.vertx.reactivex.core.Vertx;
import io.vertx.reactivex.ext.web.client.WebClient;
public class Timeout extends AbstractVerticle {
private static final int port = 8080;
private static final String host = "localhost";
private static final int timeoutMilliseconds = 50;
#Override
public void start() {
WebClient client = WebClient.create(vertx);
for (int i = 0; i < 100; i++) {
client.get(port, host, "/").timeout(timeoutMilliseconds).send(
ar -> {
if (ar.succeeded()) {
System.out.println("Success!");
} else {
System.out.println("Fail: " + ar.cause().getMessage());
}
});
}
vertx.timerStream(1000).handler(aLong -> { vertx.close(); });
}
public static void main(String[] args) {
Vertx vertx = Vertx.vertx();
vertx.deployVerticle(new Timeout());
}
}
I'm running the following Go server on the same host for testing:
package main
import (
"fmt"
"net/http"
)
func main() {
http.HandleFunc("/", HelloServer)
http.ListenAndServe(":8080", nil)
}
func HelloServer(w http.ResponseWriter, r *http.Request) {
fmt.Println("Saying hello!")
fmt.Fprintf(w, "Hello, %s!", r.URL.Path[1:])
}
The output for my test server shows that WebClient opens 5 concurrent connections and every request is stopped by the timeout. What am I doing wrong here? How should I set a connection timeout on the requests? The output from the client is:
Fail: The timeout period of 50ms has been exceeded while executing GET / for server localhost:8080
Fail: The timeout period of 50ms has been exceeded while executing GET / for server localhost:8080
Fail: The timeout period of 50ms has been exceeded while executing GET / for server localhost:8080
Fail: The timeout period of 50ms has been exceeded while executing GET / for server localhost:8080
Fail: The timeout period of 50ms has been exceeded while executing GET / for server localhost:8080
Fail: The timeout period of 50ms has been exceeded while executing GET / for server localhost:8080
Fail: The timeout period of 50ms has been exceeded while executing GET / for server localhost:8080
...
I would expect to only see "Success!" printed, since the Go server running on the same host should respond well within 50ms.
EDIT: Removed the vertx.close() and clarified original question... Didn't actually have the vertx.close() in my original test code, but added it when editing the SO post, so people running it wouldn't need to hit CTRL-C.

Answer 1

It hangs because you are blocking the main thread.
Remove this:
try {
Thread.sleep(1000);
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
vertx.close();
The application will keep running as long as vert.x is alive.
If you really want to close vert.x yourself, do it in a separate thread.
Or alternatively, do it with Vert.x itself:
vertx.timerStream(1000).handler(aLong -> {
vertx.close();
});

Answer 2

not sure what you are trying to do there, but there are multiple things that are incorrect there:
in AbstractVerticle.start() you do only start logic. also if you have async logic, then you need to use an async interface like start(Promise<Void> startPromise) and report completion properly so that Vertx waits for your start logic to finish.
you are blocking the start process here:
try {
Thread.sleep(1000);
} catch(InterruptedException ex) {
Thread.currentThread().interrupt();
}
as long as this runs, your verticle is not really started and main thread of vertx is blocked.
you never close vertx in a verticle's start! so remove this line vertx.close() and quit the running application in another way.
in general check docs to understand the process and usage of verticles.