Java Concurrency 简明教程

newCachedThreadPool Method

可以通过调用 Executors 类的静态 newCachedThreadPool() 方法获得一个缓存线程池。

A cached thread pool can be obtainted by calling the static newCachedThreadPool() method of Executors class.

Syntax

ExecutorService executor = Executors.newCachedThreadPool();

其中

where

  1. newCachedThreadPool method creates an executor having an expandable thread pool.

  2. Such an executor is suitable for applications that launch many short-lived tasks.

Example

以下 TestThread 程序展示了在基于线程的环境中使用 newCachedThreadPool 方法。

The following TestThread program shows usage of newCachedThreadPool method in thread based environment.

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class TestThread {

   public static void main(final String[] arguments) throws InterruptedException {
      ExecutorService executor = Executors.newCachedThreadPool();

      // Cast the object to its class type
      ThreadPoolExecutor pool = (ThreadPoolExecutor) executor;

      //Stats before tasks execution
      System.out.println("Largest executions: "
         + pool.getLargestPoolSize());
      System.out.println("Maximum allowed threads: "
         + pool.getMaximumPoolSize());
      System.out.println("Current threads in pool: "
         + pool.getPoolSize());
      System.out.println("Currently executing threads: "
         + pool.getActiveCount());
      System.out.println("Total number of threads(ever scheduled): "
         + pool.getTaskCount());

      executor.submit(new Task());
      executor.submit(new Task());

      //Stats after tasks execution
      System.out.println("Core threads: " + pool.getCorePoolSize());
      System.out.println("Largest executions: "
         + pool.getLargestPoolSize());
      System.out.println("Maximum allowed threads: "
         + pool.getMaximumPoolSize());
      System.out.println("Current threads in pool: "
         + pool.getPoolSize());
      System.out.println("Currently executing threads: "
         + pool.getActiveCount());
      System.out.println("Total number of threads(ever scheduled): "
         + pool.getTaskCount());

      executor.shutdown();
   }

   static class Task implements Runnable {

      public void run() {

         try {
            Long duration = (long) (Math.random() * 5);
            System.out.println("Running Task! Thread Name: " +
               Thread.currentThread().getName());
               TimeUnit.SECONDS.sleep(duration);
            System.out.println("Task Completed! Thread Name: " +
               Thread.currentThread().getName());
         } catch (InterruptedException e) {
            e.printStackTrace();
         }
      }
   }
}

这将产生以下结果。

This will produce the following result.

Output

Largest executions: 0
Maximum allowed threads: 2147483647
Current threads in pool: 0
Currently executing threads: 0
Total number of threads(ever scheduled): 0
Core threads: 0
Largest executions: 2
Maximum allowed threads: 2147483647
Current threads in pool: 2
Currently executing threads: 2
Total number of threads(ever scheduled): 2
Running Task! Thread Name: pool-1-thread-1
Running Task! Thread Name: pool-1-thread-2
Task Completed! Thread Name: pool-1-thread-2
Task Completed! Thread Name: pool-1-thread-1