如何实现ExecutorService以轮换为基础执行任务？ [英] How to implement an ExecutorService to execute tasks on a rotation-basis?

问题描述

我正在使用 java.util。 concurrent.ExecutorService with 修复线程池以执行任务列表。我的任务列表通常在80到150左右，我将任何时候运行的线程数限制为10，如下所示：

  ExecutorService threadPoolService = Executors.newFixedThreadPool（10）; 
 
 for（Runnable task：myTasks）
 {
 threadPoolService.submit（task）; 
} 
  

我的用例要求即使完成的任务也应该重新提交给 ExecutorService 但只有在所有已经提交的任务都得到服务/完成时才应该执行/重新执行。基本上，提交的任务应该以轮换方式执行。因此，在这种情况下，将不会有 threadPoolService.shutdown（）或 threadPoolService.shutdownNow（）调用。 / p>

我的问题是，如何实现 ExecutorService 服务轮换基础任务？

解决方案

ThreadPoolExecutor为afterExecution提供了一个扩展点，您可以将作业放回队列末尾。

  public class TaskRepeatingThreadPoolExecutor extends ThreadPoolExecutor {
 
 public TaskRepeatingThreadPoolExecutor（int corePoolSize，int maximumPoolSize，long keepAliveTime，TimeUnit unit，BlockingQueue< Runnable> workQueue）{
 super（corePoolSize， maximumPoolSize，keepAliveTime，unit，workQueue）; 
} 
 
 @Override 
 protected void afterExecute（Runnable r，Throwable t）{
 super.afterExecute（r，t）; 
 this.submit（r）; 
} 
} 
  

你需要做更多的工作当然要在没有 ExecutorService 的方便的工厂方法的帮助下自己实例化它，但构造函数很简单，可以理解。

I'm using java.util.concurrent.ExecutorService with fixed thread pool to execute list of tasks. My list of tasks will typically be around 80 - 150 and I've limited the number of threads running at any time to 10 as shown below:

ExecutorService threadPoolService = Executors.newFixedThreadPool(10);

for ( Runnable task : myTasks ) 
{     
    threadPoolService.submit(task); 
}

My use case demands that even the completed task should be re-submitted again to the ExecutorService but it should be executed/taken again only when all the already submitted tasks are serviced/completed. That is basically, the tasks submitted should be executed on a rotation-basis. Hence, there will not be either threadPoolService.shutdown() or threadPoolService.shutdownNow() call in this case.

My question is, how do I implement ExecutorService servicing rotation-basis tasks?

解决方案

ThreadPoolExecutor provides an extension point for afterExecution where you can put the job back at the end of the queue.

public class TaskRepeatingThreadPoolExecutor extends ThreadPoolExecutor {

    public TaskRepeatingThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
    }

    @Override
    protected void afterExecute(Runnable r, Throwable t) {
        super.afterExecute(r, t);
        this.submit(r);
    }
}

You'll have to do a little more work of course to instantiate it yourself without the help of ExecutorService's handy factory method, but the constructors are simple enough to grok.

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