Tech&W_ProgrammingBasic_Java_concurrency

concurrency 

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线程池大小设置

 

N(threads) =  N(cpu cores) + U(use rate) + ( 1 + W/C)

处理器核心数 +  期望利用率( 0 - 1)  +  等待时间 除以 计算时间

Runtime.getRuntime().available Processors()

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2020-06-09

public void concurrentAccessFromMultipleThreads() throws Exception{
        final CountDownLatchDemo.Counter counter = new CountDownLatchDemo.Counter();

        final int numberOfThread = 10;
        final CountDownLatch allThreadsComplete =
                new CountDownLatch(numberOfThread);  // 同步锁存器

        final int callsPerThread = 100;
        final Set<Long> values  = new HashSet<Long>();
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < callsPerThread; i++) {
                    values.add(counter.getAndIncrement());

                }
                allThreadsComplete.countDown();   // 将线程标记为完成
            }
        };

        for (int i = 0; i < numberOfThread; i++) {
            new Thread(runnable).start();
        }
        allThreadsComplete.await(10, TimeUnit.MINUTES); // 等待线程完成

        int expectedNoOfValues = numberOfThread * callsPerThread;
        assertEquals(expectedNoOfValues, values.size());
    }

public class CountDownLatchDemo {

    public static class Counter {
        public AtomicLong count = new AtomicLong(1);

        public long getAndIncrement() {
            return count.getAndIncrement();
        }
    }
}

 

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configurate Executor

Daemon

线程数量   n = N(cpu core) + U（use rate ) + ( w/u + 1)   等待与计算时间比率

 

 

 

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