java - Java Executor 的多线程

Question

我遇到了以下问题。比如说，我有一个包含 1000 个项目的请求，我想利用 Java Executor 来解决这个问题。

这里是主要方法

public static void main(String[] args) {

     //Assume that I have request object that contain arrayList of names
     //and VectorList is container for each request result

     ExecutorService threadExecutor = Executors.newFixedThreadPool(3);
     Vector<Result> vectorList = new Vector<Result();

     for (int i=0;i<request.size();i++) {
          threadExecutor.execute(new QueryTask(request.get(i).getNames, vectorList)
     }

      threadExecutor.shutdown();

      response.setResult(vectorList)

}

这是 QueryTask 类

public QueryTask() implements Runnable {

    private String names;
    private Vector<Result> vectorList;

    public QueryTask(String names, Vector<Result> vectorList) {
          this.names = names;
          this.vectorList = vectorList;
    }

    public void run() {
         // do something with names, for example, query database
         Result result = process names;

         //add result to vectorList
         vectorList.add(result);
    }


}

因此，基于上面的示例，我想为请求中的每个数据创建线程池，同时运行它，并将结果添加到 VectorList。在流程结束时，我希望所有结果都已在 Vector 列表中。

我一直在响应中得到不一致的结果。例如，如果我传递包含 10 个名称的请求，我只会返回 3 或 4 个，有时响应中什么也没有。我期待如果我通过 10，那么我会得到 10。

有谁知道是什么导致了这个问题？

任何帮助将不胜感激。

谢谢

Answer 1

简单的解决方案是添加对 ExecutorService.awaitTermination() 的调用

public static void main(String[] args) {

     //Assume that I have request object that contain arrayList of names
     //and VectorList is container for each request result

     ExecutorService threadExecutor = Executors.newFixedThreadPool(3);
     Vector<Result> vectorList = new Vector<Result();

     for (int i=0;i<request.size();i++) {
          threadExecutor.execute(new QueryTask(request.get(i).getNames, vectorList)
     }

      threadExecutor.shutdown();
      threadExecutor.awaitTermination(aReallyLongTime,TimeUnit.SECONDS);

      response.setResult(vectorList)

}