Swingworker实例不同时运行 [英] Swingworker instances not running concurrently

问题描述

我的电脑有4个内核，我正在运行Java swing gui程序。当我运行我的应用程序时，它只使用两个内核和大约30％的CPU利用率。我有大量要处理的文件，并希望将它们分成两个线程，以便使用更多的cpu更快地完成这项任务。

My computer has 4 cores and I am running a Java swing gui program. When I run my application it only uses two cores and about 30% CPU utilization. I have a large number of files to process and want to split them up into two threads to get this task done faster using more cpu.

我有一个名为PrepareTask的SwingWorker类，它有一个带有两个整数的构造函数：

I have a SwingWorker class called PrepareTask, that has a constructor with two ints:

class PrepareTask extends SwingWorker<Void, Void> {
  int start, end;
  PrepareTask (int start, int end) { ... }
  ...
    public Void doInBackground() {... }
    public void done() { ... }

我创建了两个这样的实例：

I create two instances of this like:

  PrepareTask prepareTask = new PrepareTask(0,numberOfFiles/2);
  prepareTask.execute();
  PrepareTask prepareTask2 = new PrepareTask(numberOfFiles/2, numberOfFiles);
  prepareTask2.execute();

两者都已启动（显示）但运行时我可以看到（打印stmts）第一个准备必须在第二个开始之前完成（在里面打印stmts）。 CPU利用率与以前相同，约为30％。他们当然都从同一来源获取数据，一个DefaultTableModel。

Both are launched (it appears) but when it runs I can see (print stmts) that the first prepare has to finish (print stmts inside) before the second one starts. And the CPU utilization is the same as before, about 30%. They both of course grab data from the same source, a DefaultTableModel.

关于如何做到这一点或我做错了什么的想法？
谢谢。

Any ideas on how to do this or what I am doing wrong? thanks.

推荐答案

这是SwingWorker从一个Java 6更新到另一个更新的行为的结果。实际上在Java 6的旧SUN bug数据库中有关于它的错误报告。

This is the result of a change in SwingWorker behaviour from one Java 6 update to another. There's actually a bug report about it in the old SUN bug database for Java 6.

SUN将原始的SwingWorker实现从使用N个线程改为使用1个线程有一个无限的队列。因此，您不能再同时运行两个SwingWorkers。 （这也会产生一种可能发生死锁的情况：如果一个swingworker等待另一个等待第一个任务，则一个任务可能会因此导致死锁。）

What happened was SUN changed the original SwingWorker implementation from using N threads, to using 1 thread with an unbounded queue. Therefore you cannot have two SwingWorkers run concurrently anymore. (This also creates a scenario where deadlock may occur: if one swingworker waits for another which waits for the first, one task might enter a deadlock as a result.)

什么你可以做到这一点是使用ExecutorService并发布FutureTasks。这些将提供99％的SwingWorker API（SwingWorker是FutureTask派生物），您所要做的就是正确设置Executor。

What you can do to get around this is use an ExecutorService and post FutureTasks on it. These will provide 99% of the SwingWorker API (SwingWorker is a FutureTask derivative), all you have to do is set up your Executor properly.

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