Example of how to fix 'java.lang.IllegalStateException: Request has already been read' exceptions when using ClusteredSessionStore. For discussion: https://groups.google.com/forum/#!topic/vertx/928XJiz1wbI

ClusteredSessionReadException.java

import io.vertx.core.AbstractVerticle;
import io.vertx.core.Vertx;
import io.vertx.core.VertxOptions;
import io.vertx.core.http.HttpServerRequest;
import io.vertx.ext.web.Router;
import io.vertx.ext.web.handler.CookieHandler;
import io.vertx.ext.web.handler.SessionHandler;
import io.vertx.ext.web.sstore.ClusteredSessionStore;

/*
* Related to the discussion here: https://groups.google.com/forum/#!topic/vertx/928XJiz1wbI
*/
public class ClusteredSessionReadException extends AbstractVerticle {

    // Convenience method so you can run it in your IDE
    public static void main(String[] args) {
        Vertx.clusteredVertx(new VertxOptions().setClustered(true), res -> {
            res.result().deployVerticle(new ClusteredSessionReadException());
        });
    }

    @Override
    public void start() throws Exception {

        Router router = Router.router(vertx);

        router.route().handler(CookieHandler.create());

        // CHANGE START - Mark the request as paused so the Vertx ServerConnection doesn't mark the request as ended
        router.route().handler( routingContext -> {
            routingContext.request().pause();
            routingContext.next();
        });
        // CHANGE END

        router.route().handler(SessionHandler.create(ClusteredSessionStore.create(vertx)));


        router.route().handler(routingContext -> {

            HttpServerRequest req = routingContext.request();

            req.endHandler(aVoid -> {
                req.response().end("finished");
            });

            // CHANGE - Resume the request once your handlers are set up
            routingContext.request().resume();
        });

        vertx.createHttpServer().requestHandler(router::accept).listen(8080);
    }
}