可以设置流中线程的优先级吗。并行()?

是的,这是可能的。

程序如下:

1. 创建 ForkJoinWorkerThreadFactory 这将创建具有适当优先级的线程。

2. 创建 ForkJoinPool 使用上述螺纹工厂。

3. 实例化并行流。

4. 叉形连接池

类似这样:

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 从…起 http://www.baeldung.com/java-8-parallel-streams-custom-threadpool )

我认为更好的方法是 here :

public class CustomForkJoinWorkerThreadFactory implements ForkJoinWorkerThreadFactory {

    private final int threadPriority;

    public CustomForkJoinWorkerThreadFactory(int threadPriority) {
        this.threadPriority = threadPriority;
    }

    @Override           
    public ForkJoinWorkerThread newThread(ForkJoinPool pool)
    {
        final ForkJoinWorkerThread worker = ForkJoinPool.defaultForkJoinWorkerThreadFactory.newThread(pool);
        worker.setPriority(threadPriority);
        return worker;
    }
}

它允许您仍然使用“默认”ForkJoinWorkerThread,但您可以设置优先级/名称等。使用方式如下:

new ForkJoinPool(poolSize, new CustomForkJoinWorkerThreadFactory(Thread.MIN_PRIORITY), null, false);