Why is my simple Jetty server handling only 1 request at a time?

Question

I'm using Jetty for the first time.

My server setup:

server = new Server(port);
ContextHandler testContext = new ContextHandler();
testContext.setContextPath("/test");
testContext.setHandler(new TestServlet());

ContextHandlerCollection contexts = new ContextHandlerCollection();
contexts.setHandlers(new Handler[]{ testContext});

HandlerCollection handlers = new HandlerCollection();
handlers.setHandlers(new Handler[]{ contexts, new DefaultHandler() });

server.setHandler(handlers);
server.setStopAtShutdown(true);
server.start();

Test code:

public class TestServlet extends AbstractHandler
{
    @Override
    public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
    {
        System.out.println("a");
        try {
            Thread.sleep(2500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("b");
        try {
            Thread.sleep(2500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("c");
        try {
            Thread.sleep(2500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        baseRequest.setHandled(true);
    }
}

If I visit localhost/test on two different tabs, the 2nd request waits until first is finished, so my log looks like:

a
b
c
a
b
c

Why are they the requests not processed in parallel?

Answer 1

It seems that people run into this from time to time (see here for example).

But as this nicely explains - jetty is built for serving users in parallel.

So the answer is: this is not a jetty problem - but a user error; for example by running the requests from a single browser (and that browser internally serializes the requests).