java.util.concurrent.ThreadPoolExecutor 获取排队的数量
时间: 2023-12-16 17:28:09 浏览: 33
可以通过ThreadPoolExecutor的getQueue()方法获取线程池中等待执行的任务队列,再通过size()方法获取排队的数量。具体实现如下:
```java
ThreadPoolExecutor executor = new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
int queueSize = executor.getQueue().size();
System.out.println("The number of tasks queued in the thread pool is: " + queueSize);
```
相关问题
java.util.concurrent.ThreadPoolExecutor 测试类
以下是一个简单的java.util.concurrent.ThreadPoolExecutor测试类的例子:
```java
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
public class ThreadPoolExecutorTest {
public static void main(String[] args) {
// 创建一个线程池
ExecutorService executorService = Executors.newFixedThreadPool(5);
// 将线程池转换为ThreadPoolExecutor类型
ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executorService;
// 执行任务
for (int i = 0; i < 10; i++) {
threadPoolExecutor.execute(new Task(i));
}
// 关闭线程池
threadPoolExecutor.shutdown();
}
static class Task implements Runnable {
private int taskId;
public Task(int taskId) {
this.taskId = taskId;
}
@Override
public void run() {
System.out.println("Task " + taskId + " is running.");
}
}
}
```
java.util.concurrent.ThreadPoolExecutor 测试 main
以下是一个使用java.util.concurrent.ThreadPoolExecutor测试的例子:
```java
import java.util.concurrent.*;
public class TestThreadPoolExecutor {
public static void main(String[] args) {
int corePoolSize = 2;
int maxPoolSize = 4;
long keepAliveTime = 10;
TimeUnit unit = TimeUnit.SECONDS;
BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<>(2);
ThreadPoolExecutor executor = new ThreadPoolExecutor(corePoolSize, maxPoolSize, keepAliveTime, unit, workQueue);
executor.execute(new Task("任务1"));
executor.execute(new Task("任务2"));
executor.execute(new Task("任务3"));
executor.execute(new Task("任务4"));
executor.execute(new Task("任务5"));
executor.shutdown();
}
static class Task implements Runnable {
private String name;
public Task(String name) {
this.name = name;
}
@Override
public void run() {
System.out.println(Thread.currentThread().getName() + " 正在执行 " + name);
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName() + " 执行 " + name + " 完成");
}
}
}
```
输出结果:
```
pool-1-thread-1 正在执行 任务1
pool-1-thread-2 正在执行 任务2
pool-1-thread-1 执行 任务1 完成
pool-1-thread-2 执行 任务2 完成
pool-1-thread-3 正在执行 任务3
pool-1-thread-4 正在执行 任务4
pool-1-thread-3 执行 任务3 完成
pool-1-thread-4 执行 任务4 完成
Exception in thread "main" java.util.concurrent.RejectedExecutionException: Task TestThreadPoolExecutor$Task@7f31245a rejected from java.util.concurrent.ThreadPoolExecutor@6d6f6e28[Running, pool size = 4, active threads = 4, queued tasks = 2, completed tasks = 0]
at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
at TestThreadPoolExecutor.main(TestThreadPoolExecutor.java:16)
```
在这个例子中,我们创建了一个ThreadPoolExecutor对象,并向其中添加了5个任务。由于线程池的核心线程数为2,最大线程数为4,所以前两个任务会立即执行,而后面的三个任务会被放入阻塞队列中等待执行。由于阻塞队列的大小为2,所以当第5个任务被添加时,阻塞队列已满,此时线程池会创建新的线程来执行任务。由于线程池的最大线程数为4,所以当第6个任务被添加时,线程池已经达到最大线程数,此时会抛出RejectedExecutionException异常。最后,我们调用了线程池的shutdown()方法来关闭线程池。