"&的Parallel.For QUOT;对于Java？ [英] "Parallel.For" for Java?

问题描述

我想知道是否有 Parallel.For 相当于Java的.net版本？

I was wondering if there is a Parallel.For equivalent to the .net version for Java?

如果有人可以提供一个例子吗？谢谢！

If there is could someone please supply an example? thanks!

推荐答案

我猜最接近的是：

ExecutorService exec = Executors.newFixedThreadPool(SOME_NUM_OF_THREADS);
try {
    for (final Object o : list) {
        exec.submit(new Runnable() {
            @Override
            public void run() {
                // do stuff with o.
            }
        });
    }
} finally {
    exec.shutdown();
}

根据TheLQ的评论，您可以将SUM_NUM_THREADS设置为 Runtime.getRuntime（）。availableProcessors（）;

Based on TheLQ's comments, you would set SUM_NUM_THREADS to Runtime.getRuntime().availableProcessors();

编辑：决定添加基本的Parallel.For实现

Decided to add a basic "Parallel.For" implementation

public class Parallel {
    private static final int NUM_CORES = Runtime.getRuntime().availableProcessors();

    private static final ExecutorService forPool = Executors.newFixedThreadPool(NUM_CORES * 2, new NamedThreadFactory("Parallel.For"));

    public static <T> void For(final Iterable<T> elements, final Operation<T> operation) {
        try {
            // invokeAll blocks for us until all submitted tasks in the call complete
            forPool.invokeAll(createCallables(elements, operation));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public static <T> Collection<Callable<Void>> createCallables(final Iterable<T> elements, final Operation<T> operation) {
        List<Callable<Void>> callables = new LinkedList<Callable<Void>>();
        for (final T elem : elements) {
            callables.add(new Callable<Void>() {
                @Override
                public Void call() {
                    operation.perform(elem);
                    return null;
                }
            });
        }

        return callables;
    }

    public static interface Operation<T> {
        public void perform(T pParameter);
    }
}

Parallel.For的示例用法

// Collection of items to process in parallel
Collection<Integer> elems = new LinkedList<Integer>();
for (int i = 0; i < 40; ++i) {
    elems.add(i);
}
Parallel.For(elems, 
 // The operation to perform with each item
 new Parallel.Operation<Integer>() {
    public void perform(Integer param) {
        System.out.println(param);
    };
});

我想这个实现更类似于 Parallel.ForEach

I guess this implementation is really more similar to Parallel.ForEach

修改
如果有人有兴趣我把它放在GitHub上。 在GitHub上并行使用

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