一个更加健壮的ThreadPool

最新推荐文章于 2025-08-23 19:36:46 发布

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最新推荐文章于 2025-08-23 19:36:46 发布

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分类专栏：代码文章标签： java

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本文详细介绍了Dubbo框架中三种线程池的具体配置方式和特性：可伸缩线程池(CachedThreadPool)，固定大小线程池(FixedThreadPool)及受限增长线程池(LimitedThreadPool)。这些线程池在不同场景下有着各自的优势和适用范围。

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从dubbo中找到的:

/**
 * 此线程池可伸缩，线程空闲一分钟后回收，新请求重新创建线程，来源于：<code>Executors.newCachedThreadPool()</code>
 * 
 * @see java.util.concurrent.Executors#newCachedThreadPool()
 * @author william.liangf
 */
public class CachedThreadPool implements ThreadPool {

    public Executor getExecutor(URL url) {
        String name = url.getParameter(Constants.THREAD_NAME_KEY, Constants.DEFAULT_THREAD_NAME);
        int cores = url.getParameter(Constants.CORE_THREADS_KEY, Constants.DEFAULT_CORE_THREADS);
        int threads = url.getParameter(Constants.THREADS_KEY, Integer.MAX_VALUE);
        int queues = url.getParameter(Constants.QUEUES_KEY, Constants.DEFAULT_QUEUES);
        int alive = url.getParameter(Constants.ALIVE_KEY, Constants.DEFAULT_ALIVE);
        return new ThreadPoolExecutor(cores, threads, alive, TimeUnit.MILLISECONDS, 
        		queues == 0 ? new SynchronousQueue<Runnable>() : 
        			(queues < 0 ? new LinkedBlockingQueue<Runnable>() 
        					: new LinkedBlockingQueue<Runnable>(queues)),
        		new NamedThreadFactory(name, true), new AbortPolicyWithReport(name, url));
    }

}

/**
 * 此线程池启动时即创建固定大小的线程数，不做任何伸缩，来源于：<code>Executors.newFixedThreadPool()</code>
 * 
 * @see java.util.concurrent.Executors#newFixedThreadPool(int)
 * @author william.liangf
 */
public class FixedThreadPool implements ThreadPool {

    public Executor getExecutor(URL url) {
        String name = url.getParameter(Constants.THREAD_NAME_KEY, Constants.DEFAULT_THREAD_NAME);
        int threads = url.getParameter(Constants.THREADS_KEY, Constants.DEFAULT_THREADS);
        int queues = url.getParameter(Constants.QUEUES_KEY, Constants.DEFAULT_QUEUES);
        return new ThreadPoolExecutor(threads, threads, 0, TimeUnit.MILLISECONDS, 
        		queues == 0 ? new SynchronousQueue<Runnable>() : 
        			(queues < 0 ? new LinkedBlockingQueue<Runnable>() 
        					: new LinkedBlockingQueue<Runnable>(queues)),
        		new NamedThreadFactory(name, true), new AbortPolicyWithReport(name, url));
    }

}

/**
 * 此线程池一直增长，直到上限，增长后不收缩。
 * 
 * @author <a href="mailto:gang.lvg@alibaba-inc.com">kimi</a>
 */
public class LimitedThreadPool implements ThreadPool {

    public Executor getExecutor(URL url) {
        String name = url.getParameter(Constants.THREAD_NAME_KEY, Constants.DEFAULT_THREAD_NAME);
        int cores = url.getParameter(Constants.CORE_THREADS_KEY, Constants.DEFAULT_CORE_THREADS);
        int threads = url.getParameter(Constants.THREADS_KEY, Constants.DEFAULT_THREADS);
        int queues = url.getParameter(Constants.QUEUES_KEY, Constants.DEFAULT_QUEUES);
        return new ThreadPoolExecutor(cores, threads, Long.MAX_VALUE, TimeUnit.MILLISECONDS, 
        		queues == 0 ? new SynchronousQueue<Runnable>() : 
        			(queues < 0 ? new LinkedBlockingQueue<Runnable>() 
        					: new LinkedBlockingQueue<Runnable>(queues)),
        		new NamedThreadFactory(name, true), new AbortPolicyWithReport(name, url));
    }

}

public class AbortPolicyWithReport extends ThreadPoolExecutor.AbortPolicy {
    
    protected static final Logger logger = LoggerFactory.getLogger(AbortPolicyWithReport.class);
    
    private final String threadName;
    
    private final URL url;
    
    public AbortPolicyWithReport(String threadName, URL url) {
        this.threadName = threadName;
        this.url = url;
    }
    
    @Override
    public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
        String msg = String.format("Thread pool is EXHAUSTED!" +
                " Thread Name: %s, Pool Size: %d (active: %d, core: %d, max: %d, largest: %d), Task: %d (completed: %d)," +
                " Executor status:(isShutdown:%s, isTerminated:%s, isTerminating:%s), in %s://%s:%d!" ,
                threadName, e.getPoolSize(), e.getActiveCount(), e.getCorePoolSize(), e.getMaximumPoolSize(), e.getLargestPoolSize(),
                e.getTaskCount(), e.getCompletedTaskCount(), e.isShutdown(), e.isTerminated(), e.isTerminating(),
                url.getProtocol(), url.getIp(), url.getPort());
        logger.warn(msg);
        throw new RejectedExecutionException(msg);
    }

}