ThreadSample.java

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package cn.orz.pascal.example.csv;

import java.util.Arrays;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

/**
 *
 * @author koduki
 */
public class ThreadSample {

    public static void main(String[] args) throws InterruptedException, ExecutionException {
        long s, l;

        for (int i = 0; i < 5; i++) {
            s = System.nanoTime();
            executeTasks(Executors.newFixedThreadPool(100));
            l = System.nanoTime();
            System.out.println("newFixedThreadPool: " + (l - s) + " ns");
        }

        for (int i = 0; i < 5; i++) {
            s = System.nanoTime();
            executeTasks(Executors.newSingleThreadExecutor());
            l = System.nanoTime();
            System.out.println("newSingleThreadExecutor: " + (l - s) + " ns");
        }
    }

    public static void executeTasks(ExecutorService es) throws ExecutionException, InterruptedException {
        try {
            // タスクをリストに登録
            List<Callable<Integer>> tasks = Arrays.asList(
                    new ParallelTask("タスク1"),
                    new ParallelTask("タスク2"),
                    new ParallelTask("タスク3"));

            // タスクを並列実行する
            List<Future<Integer>> futures = null;
            futures = es.invokeAll(tasks);

            // 並列処理の返り値を取得する
            Integer count = 0;
            for (Future<Integer> future : futures) {
                count += future.get();

            }
            System.out.printf("カウントの合計は%sです。\n", count);
        } finally {
            if (es != null) {
                es.shutdown();
            }
        }
    }

    public static class ParallelTask implements Callable<Integer> {

        private String taskName;

        private Integer count = 0;

        public ParallelTask(String taskName) {
            this.taskName = taskName;
        }

        @Override
        public Integer call() throws Exception {
//            System.out.printf("%sの処理を開始します。カウントは%sです。\n", taskName, count);
            for (int i = 0; i < 5; i++) {
                count++;
//                System.out.printf("%s, count=%s, i=%s\n", taskName, count, i);
            }
//            System.out.printf("%sの処理を終了します。カウントは%sです。\n", taskName, count);
            return count;
        }

    }
}