具有有界队列的 Java 线程池

发布于 2024-11-14 21:05:39 字数 486 浏览 0 评论 0原文

我正在使用 java.util.concurrent 的 Executors 类，用于创建固定线程池，用于为 Web 服务器运行请求处理程序：

static ExecutorService  newFixedThreadPool(int nThreads)

描述如下：

创建一个线程池，该线程池重用一组在共享无界共享队列上运行的固定线程。

但是，我正在寻找线程池实现，它将执行完全相同的操作，除了有界队列之外。有这样的实现吗？或者我是否需要为固定线程池实现自己的包装器？

原文

I'm using java.util.concurrent's Executors class to create a fixed thread pool for running request handlers for a web server:

static ExecutorService  newFixedThreadPool(int nThreads)

and the description is:

Creates a thread pool that reuses a fixed set of threads operating off a shared unbounded queue.

However, I am looking for thread pool implementation which will do the exact same thing, except with a bounded queue. Is there such an implementation? Or do I need to implement my own wrapper for the fixed thread pool?

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苏佲洛 2024-11-21 21:05:39

您想要做的是新建自己的 ExecutorService，可能使用 ThreadPoolExecutor。 ThreadPoolExecutor 有一个构造函数，它接受 BlockingQueue 并获取您使用的有界队列，例如 ArrayBlockingQueue 正确构建边界。您还可以包含 RejectedExecutionHandler 以确定队列已满时要做什么，或者保留对阻塞队列的引用并使用 Offer 方法。

这是一个小例子：

BlockingQueue<Runnable> linkedBlockingDeque = new LinkedBlockingDeque<Runnable>(
    100);
ExecutorService executorService = new ThreadPoolExecutor(1, 10, 30,
    TimeUnit.SECONDS, linkedBlockingDeque,
    new ThreadPoolExecutor.CallerRunsPolicy());

What you want to do is new your own ExecutorService, probably using ThreadPoolExecutor. ThreadPoolExecutor has a constructor which takes a BlockingQueue and to get a bounded queue you use for example ArrayBlockingQueue properly constructed for bounding. You can also include a RejectedExecutionHandler in order to determine what to do when your queue is full, or hang on to a reference to the blocking queue and use the offer methods.

Here's a mini example:

BlockingQueue<Runnable> linkedBlockingDeque = new LinkedBlockingDeque<Runnable>(
    100);
ExecutorService executorService = new ThreadPoolExecutor(1, 10, 30,
    TimeUnit.SECONDS, linkedBlockingDeque,
    new ThreadPoolExecutor.CallerRunsPolicy());

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嘿嘿嘿 2024-11-21 21:05:39

创建一个ThreadPoolexecutor 并在其中传递合适的 BlockingQueue 实现。例如，您可以传入 ArrayBlockingQueue 在ThreadPoolExecutor构造函数中得到想要的效果。

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不必你懂 2024-11-21 21:05:39

我已经用 Semaphore 我用它来限制提交给 ExecutorService 的任务。

例如：

int threadCount = 10;
ExecutorService consumerPool = Executors.newFixedThreadPool(threadCount);

// set the permit count greater than thread count so that we 
// build up a limited buffer of waiting consumers
Semaphore semaphore = new Semaphore(threadCount * 100); 

for (int i = 0; i < 1000000; ++i) {
    semaphore.acquire(); // this might block waiting for a permit 
    Runnable consumer = () -> {
       try {
          doSomeWork(i);
       } finally {
          semaphore.release(); // release a permit 
       }
    };
    consumerPool.submit(consumer);
}

I've solved this with a Semaphore which I use to throttle tasks being submitted to the ExecutorService.

Eg:

int threadCount = 10;
ExecutorService consumerPool = Executors.newFixedThreadPool(threadCount);

// set the permit count greater than thread count so that we 
// build up a limited buffer of waiting consumers
Semaphore semaphore = new Semaphore(threadCount * 100); 

for (int i = 0; i < 1000000; ++i) {
    semaphore.acquire(); // this might block waiting for a permit 
    Runnable consumer = () -> {
       try {
          doSomeWork(i);
       } finally {
          semaphore.release(); // release a permit 
       }
    };
    consumerPool.submit(consumer);
}

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