构建一个七参数的线程池

构建七个参数的线程池，

public static final ThreadPoolExecutor threadPoolExecutor 
    = new ThreadPoolExecutor(
    10,   //corePoolSize
    20,   //maximumPoolSize
    60,   //keepAliveTime
    TimeUnit.SECONDS,  //TimeUnit
    new LinkedBlockingQueue<Runnable>(),   //BlockingQueue<Runnable>
    Executors.defaultThreadFactory(),  //ThreadFactory
    new ThreadPoolExecutor.CallerRunsPolicy());  //RejectedExecutionHandler

corePoolSize大小：

　　一般需要根据任务的类型来配置线程池大小：

　　如果是CPU密集型任务，应配置尽可能小的线程，参考值可以设为 NCPU+1

　　如果是IO密集型任务，由于IO密集型任务中线程并不是一直在执行任务，则应配置尽可能多的线程，参考值可以设置为2*NCPU

　　具体的设置需要根据实际情况进行调整，比如可以先将线程池大小设置为参考值，再观察任务运行情况和系统负载、资源利用率来进行适当调整。

ThreadFactory

　　Executors提供的默认的实现

    /**
     * The default thread factory
     */
    static class DefaultThreadFactory implements ThreadFactory {
        private static final AtomicInteger poolNumber = new AtomicInteger(1);
        private final ThreadGroup group;
        private final AtomicInteger threadNumber = new AtomicInteger(1);
        private final String namePrefix;

        DefaultThreadFactory() {
            SecurityManager s = System.getSecurityManager();
            group = (s != null) ? s.getThreadGroup() :
                                  Thread.currentThread().getThreadGroup();
            namePrefix = "pool-" +
                          poolNumber.getAndIncrement() +
                         "-thread-";
        }

        public Thread newThread(Runnable r) {
            Thread t = new Thread(group, r,
                                  namePrefix + threadNumber.getAndIncrement(),
                                  0);
            if (t.isDaemon())
                t.setDaemon(false);
            if (t.getPriority() != Thread.NORM_PRIORITY)
                t.setPriority(Thread.NORM_PRIORITY);
            return t;
        }
    }

        我们可以参考它来实现自己的线程工厂并重命名，也可以使用guava的ThreadFactoryBuilder()来创建

public static ThreadFactory threadFactory = new ThreadFactoryBuilder().setNameFormat("pay-verify-task-%d").build();

拒绝策略

 

AbortPolicy	默认：直接抛出RejectedExecutionException异常
CallerRunsPolicy	任务被拒绝添加后，会调用当前线程池的所在的线程去执行被拒绝的任务
DiscardPolicy	直接抛弃，不会抛异常也不会执行
DiscardOldestPolicy	抛弃任务队列中最旧的任务也就是最先加入队列的，再把这个新任务添加进去

 

 

 

 

 

 

 

 

 

 

 

 

参考文章：Java并发编程：线程池的使用 https://www.cnblogs.com/dolphin0520/p/3932921.html