如何执行异步计算并同时处理其他http请求？

Question

I want to handle several http request simultaneously. What means that I want the thread that get the http request will move the handle of the request to another thread and will be available for getting new requests, until the handler will provide the result. I will appreciate if someone can show me how to it right. Thanks!

I tried working with CompletableFuture, but apparently I am doing something wrong, since the thread that gets the request is blocked for getting new requests until the handler finished.

As you can see - only after the handler finished (10 seconds of sleep) - the request thread get the new request, so I have no advantage that the handler was executed in another thread.

@GET
@Path("/{phoneNumber}")
@Produces(MediaType.APPLICATION_JSON)
public Response query() throws InterruptedException, ExecutionException 
{   
    log.debug("get a request");                                         
    String message = calculateAsync().get();
    return Response.ok(message).build();
}

public Future<String> calculateAsync() throws InterruptedException 
{
    CompletableFuture<String> completableFuture = new CompletableFuture<String>();
    completableFuture = CompletableFuture.supplyAsync(() -> 
        {
            try {
                Thread.sleep(10000);
                log.debug("finish waiting");
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return "hello";
        });
    return completableFuture;
}

2019-06-21 06:38:48,080 DEBUG [grizzly-http-server-0] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - get a request 2019-06-21 06:38:58,081 DEBUG [ForkJoinPool.commonPool-worker-1] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - finish waiting 2019-06-21 06:38:58,116 DEBUG [grizzly-http-server-0] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - get a request 2019-06-21 06:39:08,113 DEBUG [ForkJoinPool.commonPool-worker-1] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - finish waiting

Answer 1

I found a way to do it not using completableFuture (that I am still don't understand how it is useful, if in the end you need to call the get() method and be blocked until it ends), but using the @Suspended AsyncResponse response , like agpt suggested.

Here is the code:

  @GET
  @Path("/{phoneNumber}")
  @Consumes("application/json")
   public void submit(@PathParam("phoneNumber") String phoneNumber, final @Suspended AsyncResponse response1) {
      log.debug("get a request " +phoneNumber);
      new Thread() {
         public void run() {
            String confirmation = process(phoneNumber);
            Response response = Response.ok(confirmation,
                                            MediaType.APPLICATION_XML_TYPE)
                                        .build();
            response1.resume(response);
         }
      }.start();
      log.debug("the submit finish " + phoneNumber);
   }


  public String process(String phoneNumber)
  {
        try {
            Thread.sleep(10000);
            log.debug("finish waiting "+phoneNumber);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        String res = "hello" + phoneNumber;
        return res;
  }

2019-06-23 09:54:20,157 DEBUG [grizzly-http-server-0] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - get a request 1 2019-06-23 09:54:20,158 DEBUG [grizzly-http-server-0] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - the submit finish 1 2019-06-23 09:54:22,026 DEBUG [grizzly-http-server-0] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - get a request 2 2019-06-23 09:54:22,026 DEBUG [grizzly-http-server-0] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - the submit finish 2 2019-06-23 09:54:30,158 DEBUG [Thread-2] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - finish waiting 1 2019-06-23 09:54:32,027 DEBUG [Thread-3] [com.xconnect.np.test.superquery.suppliers.http.QueryResource] - finish waiting 2