executorservice | 易学教程

Executor框架+实例

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Executor框架是指java 5中引入的一系列并发库中与executor相关的一些功能类，其中包括线程池，Executor，Executors，ExecutorService，CompletionService，Future，Callable等。 Executor框架简介 Executor框架描述 Executor框架是指java 5中引入的一系列并发库中与executor相关的一些功能类，其中包括线程池，Executor，Executors，ExecutorService，CompletionService，Future，Callable等。运用该框架能够很好的将任务分成一个个的子任务，使并发编程变得方便。 Executor相关类图该框架的类图（方法并没有都表示出来）如下：创建线程池类别创建线程池 Executors类，提供了一系列工厂方法用于创先线程池，返回的线程池都实现了ExecutorService接口。 public static ExecutorService newFixedThreadPool(int nThreads) 创建固定数目线程的线程池 public static ExecutorService newCachedThreadPool() 创建一个可缓存的线程池创建一个可缓存的线程池，调用execute 将重用以前构造的线程

java并发库之Executors常用的创建ExecutorService的几个方法说明

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一、线程池的创建我们可以通过ThreadPoolExecutor来创建一个线程池。 new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepAliveTime, milliseconds,runnableTaskQueue, handler); 创建一个线程池需要输入几个参数： corePoolSize（线程池的基本大小）：当提交一个任务到线程池时，线程池会创建一个线程来执行任务，即使其他空闲的基本线程能够执行新任务也会创建线程，等到需要执行的任务数大于线程池基本大小时就不再创建。如果调用了线程池的prestartAllCoreThreads方法，线程池会提前创建并启动所有基本线程。 runnableTaskQueue（任务队列）：用于保存等待执行的任务的阻塞队列。可以选择以下几个阻塞队列。 ArrayBlockingQueue：是一个基于数组结构的有界阻塞队列，此队列按 FIFO（先进先出）原则对元素进行排序。 LinkedBlockingQueue：一个基于链表结构的阻塞队列，此队列按FIFO （先进先出）排序元素，吞吐量通常要高于ArrayBlockingQueue。静态工厂方法Executors.newFixedThreadPool()使用了这个队列。 SynchronousQueue

How to call same method of a different class in multithreaded way

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问题 I have a method named process in two of my Classes, lets say CLASS-A and CLASS-B . Now in the below loop, I am calling process method of both of my classes sequentially meaning one by one and it works fine but that is the not the way I am looking for. for (ModuleRegistration.ModulesHolderEntry entry : ModuleRegistration.getInstance()) { final Map<String, String> response = entry.getPlugin().process(outputs); // write to database System.out.println(response); } Is there any way, I can call the

How to call same method of a different class in multithreaded way

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多线程IO操作(扫描文件夹并计算总大小)

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场景为，给到一个硬盘上文件或文件夹，（当然文件夹时，多线程的优势才能越发体现出来），得到该文件或文件夹的大小和计算该结果所需要的时间。首先是单线程下的例子，这个可难不倒大家，代码如下： public class TotalFileSizeSequential { private long getTotalSizeOfFilesInDir(final File file) { if (file.isFile()) return file.length(); final File[] children = file.listFiles(); long total = 0; if (children != null) for(final File child : children) total += getTotalSizeOfFilesInDir(child); return total; } public static void main(final String[] args) { final long start = System.nanoTime(); final long total = new TotalFileSizeSequential() .getTotalSizeOfFilesInDir(new File("D:/idea_ws")); final long

ScheduledExecutorService: when shutdown should be invoked?

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问题 I use ScheduledExecutorService in my application. I need to use it from time to time in certain Utility class to run scheduled threads. Is it a good design to hold ScheduledExecutorService in static field? Is it a must to invoke ScheduledExecutorService.shutdown() in such case? What is the risk if I do not invoke shutdown? That's what I thought to do: private static ScheduledExecutorService exec = Executors.newScheduledThreadPool(5); public void scheduleTask(String name) { Future<?> future =

How to use custom executor in Akka dispatcher

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问题 I am trying to use a custom executor for a dispatcher in Akka. Specifically, I want to wrap an existing executor with my own (logging, debugging, etc.). I've looked at relevant parts of documentation: The default dispatcher can be configured, and is by default a Dispatcher with a “fork-join-executor”, which gives excellent performance in most cases. and specify using “executor” using “fork-join-executor”, “thread-pool-executor” or the FQCN of an akka.dispatcher.ExecutorServiceConfigurator (I

Runnable locked (park) using ExecutorService and BlockingQueue

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问题 Note: I understand the rules site, but I can't to put all code (complex/large code). I wish I was more specific, but I don't know what part to extract and show. Before you close this question: Obviously, I am willing to refine my question if someone tells me where to look (technical detail). I made a video in order to show my issue. Even to formulate the question, I made a diagram to show the situation. My program has a JTree , showing the relations between Worker . I have a diagram

invokeAll() is not willing to accept a Collection<Callable<T>>

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问题 I fail to understand why this code won't compile ExecutorService executor = new ScheduledThreadPoolExecutor(threads); class DocFeeder implements Callable<Boolean> {....} ... List<DocFeeder> list = new LinkedList<DocFeeder>(); list.add(new DocFeeder(1)); ... executor.invokeAll(list); The error msg is: The method invokeAll(Collection<Callable<T>>) in the type ExecutorService is not applicable for the arguments (List<DocFeeder>) list is a Collection of DocFeeder , which implements Callable

How can I set Socket write timout in java?

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问题 I have a problem with handling socket in java. I am running a TCP server with multiple client connections. For performance reason, I used a simple thread pool to handle packets. Please see code below public enum LazyWorkCenter { instance; LazyWorkCenter() { lazyWorker = new NamedThreadPoolExecutor(3,3, 0L,TimeUnit.MILLISECONDS, "LazyWorker"); } private ExecutorService lazyWorker ; public void executeLazy(Runnable lazyTask) { lazyWorker.execute(lazyTask); } } public class TcpServerForClient {