java - 是否可以在 Stream.parallel() 中设置线程的优先级？

Question

如果我想在后台任务中并行运行一个流，是否可以以较低的优先级运行它？如果是这样的话？

Answer 1

是的，这是可能的。

过程如下:

1. 创建一个 ForkJoinWorkerThreadFactory 以创建具有适当优先级的线程。

2. 使用上述线程工厂创建一个ForkJoinPool。

3. 实例化并行流。

4. 通过将流提交到 ForkJoinPool

来运行流

像这样:

public class MyThread extends ForkJoinWorkerThread {
    public MyThread(ForkJoinPool pool, int priority) {
        super(pool);
        setPriority(priority);
    }
}

final int poolSize = ...
final int priority = ...

List<Long> aList = LongStream.rangeClosed(firstNum, lastNum).boxed()
  .collect(Collectors.toList());

ForkJoinWorkerThreadFactory factory = new ForkJoinWorkerThreadFactory() {
    public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
         return new MyThread(pool, priority);
    }
};
/*
ForkJoinWorkerThreadFactory factory = pool -> new MyThread(
  pool,
  priority
);
*/

ForkJoinPool customThreadPool = new ForkJoinPool(
    poolSize, factory, null, false);
long actualTotal = customThreadPool.submit(
    () -> aList.parallelStream().reduce(0L, Long::sum)).get();

(示例代码改编自http://www.baeldung.com/java-8-parallel-streams-custom-threadpool)