Multithreading JavaEE：线程中的构建和刷新响应

我正在尝试编写一个线程化的JavaEEservlet。 每个线程将使用HTTP传输编码：chunked在单个HTTP块中执行一些处理并写入其结果。 每个数据块一可用就会被发送到客户端。 我在每个线程中写入和刷新输出时遇到问题。 例如，下面的代码生成5个线程，这些线程生成一个随机字符串，将其写入输出缓冲区，并通过同步函数调用刷新该缓冲区

public class TestServer extends HttpServlet {
   private PrintWriter m_out;

   public TestServer() {
      super();
   }

   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      m_out = response.getWriter();

      m_out.print("gonna start\n");
      m_out.flush();

      ThreadPoolExecutor thread_pool = (ThreadPoolExecutor) Executors.newFixedThreadPool(10);
      for(int i = 0; i < 5; i++ ) {
         thread_pool.execute(new Runnable() {
        private ReentrantLock m_lock = new ReentrantLock();
        @Override
        public void run() {
               SecureRandom random = new SecureRandom();
               m_lock.lock();
               try {
                  display(new BigInteger(1300, random).toString(32)+"\n");
               }
               finally {
                  m_lock.unlock();
               }
            }
         });
      }
      thread_pool.shutdown();
      try {
         thread_pool.awaitTermination(120, TimeUnit.SECONDS);
      }
      catch (InterruptedException e1) {
         log("thread interrupted");
         e1.printStackTrace();
      }
      m_out.print("ok we done\n");
      m_out.close();
   }

   void display(String content) {
      m_out.print(content);
      m_out.flush();
   }
}

您可以看到，第一个动态生成的行是重复的。 这似乎表明PrintWriter.flush方法无法同步

为什么这不起作用，我能做些什么来实现我的目标

---

谢谢。

为了将来的参考，我想我用以下代码实现了它：

@SuppressWarnings("serial")
public class TestServer extends HttpServlet {
   private final int THREADPOOL_SIZE = 10;
   private ThreadPoolExecutor thread_pool;

   public void init(ServletConfig config) throws ServletException {
      super.init(config);
      thread_pool = (ThreadPoolExecutor) Executors.newFixedThreadPool(THREADPOOL_SIZE);
   }

   public void destroy() {
      thread_pool.shutdownNow();
   }

   public TestServer() {
          super();
   }

   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      CompletionService<String> completion_service_pool = new ExecutorCompletionService<String>(thread_pool);
      int task_num = 10;
      final int line_length = 13000;
      for(int i = 0; i < task_num; i++) {
         completion_service_pool.submit(new Callable<String>(){
            @Override
            public String call() {
               Random rn = new Random();
               int sleep_seconds = Math.abs(rn.nextInt() % 10);
               try {
                  Thread.sleep(sleep_seconds * 1000);
               }
               catch (Exception e) {

               }
               return String.format("Slept for %d seconds. %s<br>\n", sleep_seconds, new BigInteger(line_length, rn).toString(32));
            }
         });
      }

      PrintWriter out = response.getWriter();
      response.setContentType("text/html");
      out.print("gonna start<br>\n");
      out.flush();

      for(int i = 0; i < task_num; ) {
         try {
            Future<String> result_task = completion_service_pool.poll();
            if(result_task != null) {
               String result_string = result_task.get();
               out.print(result_string);
               out.flush();
               i++;
            }
         }
         catch (Exception e) {
         }
      }

      out.print("ok we done<br>\n");
      out.close();
   }
}

@SuppressWarnings("serial")
public class TestServer extends HttpServlet {
   private final int THREADPOOL_SIZE = 10;
   private ThreadPoolExecutor thread_pool;

   public void init(ServletConfig config) throws ServletException {
      super.init(config);
      thread_pool = (ThreadPoolExecutor) Executors.newFixedThreadPool(THREADPOOL_SIZE);
   }

   public void destroy() {
      thread_pool.shutdownNow();
   }

   public TestServer() {
          super();
   }

   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      CompletionService<String> completion_service_pool = new ExecutorCompletionService<String>(thread_pool);
      int task_num = 10;
      final int line_length = 13000;
      for(int i = 0; i < task_num; i++) {
         completion_service_pool.submit(new Callable<String>(){
            @Override
            public String call() {
               Random rn = new Random();
               int sleep_seconds = Math.abs(rn.nextInt() % 10);
               try {
                  Thread.sleep(sleep_seconds * 1000);
               }
               catch (Exception e) {

               }
               return String.format("Slept for %d seconds. %s<br>\n", sleep_seconds, new BigInteger(line_length, rn).toString(32));
            }
         });
      }

      PrintWriter out = response.getWriter();
      response.setContentType("text/html");
      out.print("gonna start<br>\n");
      out.flush();

      for(int i = 0; i < task_num; ) {
         try {
            Future<String> result_task = completion_service_pool.poll();
            if(result_task != null) {
               String result_string = result_task.get();
               out.print(result_string);
               out.flush();
               i++;
            }
         }
         catch (Exception e) {
         }
      }

      out.print("ok we done<br>\n");
      out.close();
   }
}