java线程池实例演示

线程池实例演示

作者: dugang QQ:53732908
/ajf8/home
/dyyx007


*********************************************java代码

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.ThreadPoolExecutor.AbortPolicy;

/**
* 线程池例子
*
* @author gang.dug qq:53732908
*/
public class ThreadPoolTest {

private static final long TASK_SLEEP_TIME = 3000;
private static final String FULL_DATE_FORMAT = "yyyy-MM-dd HH:mm:ss SSS";
private static DateFormat dateFormat = new SimpleDateFormat(FULL_DATE_FORMAT);

public static void main(String[] args) throws Exception {
// 线程池 数据库连接池 可联系起来
int corePoolSize = 3;// minPoolSize
int maxPoolSize = 5;
long keepAliveTime = 10;
TimeUnit unit = TimeUnit.SECONDS;
int maxTaskSize = 5;// 任务队列最大容量
// 任务队列
BlockingQueue workQueue = new LinkedBlockingQueue(maxTaskSize);
// 饱和处理策略
RejectedExecutionHandler handler = new AbortPolicy();
ThreadPoolExecutor pool = null;
// 创建线程池
pool = new ThreadPoolExecutor(corePoolSize, maxPoolSize, keepAliveTime, unit, workQueue, handler);
// 生产者消费者队列 阻塞队列
// 任务先提交到任务队列
// 线程池中线程 从任务队列里获取任务并执行
// 任务需要实现Runnable接口

// corePoolSize //核心池的大小 minPoolSize
// maxPoolSize //最大池的大小
// keepAliveTime //超出corePoolSize时 线程最大空闲时间
// workQueue //任务队列
// handler //饱和策略
// 何时执行饱和策略 线程个数==maxPoolSize && 任务队列已满

// 各种饱和策略
// AbortPolicy 抛异常RejectedExecutionException
// CallerRunsPolicy 调度者执行
// DiscardOldestPolicy放弃最旧的未处理请求，执行新传入的任务
// DiscardPolicy 不做任何操作，放弃新任务

System.out.println(getPoolInfo(pool));
// poolSize=0,activeCount=0,completedTaskCount=0,taskCount=0,taskWaitCount=0
Runnable r = null;

r = new MyTask("thread0");
pool.execute(r);
Thread.sleep(100);
System.out.println(getPoolInfo(pool));
// poolSize=1,activeCount=1,completedTaskCount=0,taskCount=1,taskWaitCount=0
Thread.sleep(TASK_SLEEP_TIME + 200);
System.out.println(getPoolInfo(pool));
// 第一个任务执行完成 activeCount=0,complet

edTaskCount=1
// poolSize=1,activeCount=0,completedTaskCount=1,taskCount=1,taskWaitCount=0
// 任务执行 抛出异常的情况
r = new MyTask("errorThread", true);
pool.execute(r);
Thread.sleep(100);
System.out.println(getPoolInfo(pool));
// 抛出异常的任务不统计
// poolSize=1,activeCount=0,completedTaskCount=1,taskCount=1
// 任务执行异常在线程池内部抛出 外部不需要catch
for (int i = 1; i < 20; i++) {
try {
Thread.sleep(100);
r = new MyTask("thread" + i);
pool.execute(r);
System.out.println(getPoolInfo(pool));
} catch (Throwable e) {
System.out.println(e + "," + r);
}
}
// poolSize=3,activeCount=3,completedTaskCount=1,taskCount=5,taskWaitCount=1
// poolSize=3,activeCount=3,completedTaskCount=1,taskCount=6,taskWaitCount=2
// poolSize=3,activeCount=3,completedTaskCount=1,taskCount=7,taskWaitCount=3
// poolSize=3,activeCount=3,completedTaskCount=1,taskCount=8,taskWaitCount=4
// poolSize=3,activeCount=3,completedTaskCount=1,taskCount=9,taskWaitCount=5
// poolSize=4,activeCount=3,completedTaskCount=1,taskCount=9,taskWaitCount=5

// 任务队列大小 taskWaitCount = taskCount-completedTaskCount-activeCount
// 任务队列满时才会 增加线程

Thread.sleep(20000);
// 线程空闲超过 keepAliveTime 会被清理掉
// 直到线程数量为 corePoolSize/minPoolSize
System.out.println(getPoolInfo(pool));
// poolSize=3,activeCount=0,completedTaskCount=11,taskCount=11,taskWaitCount=0
// 关闭线程池 已提交的任务执行完毕后再关闭
pool.shutdown();
}

private static class MyTask implements Runnable {

private boolean throwException = false;
private String name = null;

public MyTask(String name) {
= name;
}

public MyTask(String name, boolean throwException) {
= name;
this.throwException = throwException;
}

public void run() {
if (throwException) {
throw new RuntimeException("run error,name=" + name);
}
System.out.println("MyThread " + name + " start " + now());
sleep(TASK_SLEEP_TIME);
// System.out.println("MyThread " + name + " run end " + now());
}
}

private static String getPoolInfo(ThreadPoolExecutor pool) {
String s = "";
// 线程池大小 当前工作线程数量
int poolSize = pool.getPoolSize();
// 正在运行的任务
int activeCount = pool.getActiveCount();
// 运行结束的任务
long completedTaskCount = pool.getCompletedTaskCount()

;
// 任务总数
long taskCount = pool.getTaskCount();
// 等待运行的 任务队列里的任务数量
long taskWaitCount = taskCount - completedTaskCount - activeCount;
s = s + "poolSize=" + poolSize;
s = s + ",activeCount=" + activeCount;
s = s + ",completedTaskCount=" + completedTaskCount;
s = s + ",taskCount=" + taskCount;
s = s + ",taskWaitCount=" + taskWaitCount;
return s;
}

private static void sleep(long sleeptime) {
try {
Thread.sleep(sleeptime);
} catch (Exception e) {
System.out.println(e);
}
}

private static String now() {
return dateFormat.format(new Date());
}
}




*********************************************日志输出


poolSize=0,activeCount=0,completedTaskCount=0,taskCount=0,taskWaitCount=0
MyThread thread0 start 2011-12-30 19:25:19 330
poolSize=1,activeCount=1,completedTaskCount=0,taskCount=1,taskWaitCount=0
poolSize=1,activeCount=0,completedTaskCount=1,taskCount=1,taskWaitCount=0
Exception in thread "pool-1-thread-2" ng.RuntimeException: run error,name=errorThread
at ThreadPoolTest$MyTask.run(ThreadPoolTest.java:124)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
at ng.Thread.run(Thread.java:595)
poolSize=1,activeCount=0,completedTaskCount=1,taskCount=1,taskWaitCount=0
poolSize=2,activeCount=0,completedTaskCount=1,taskCount=1,taskWaitCount=0
MyThread thread1 start 2011-12-30 19:25:22 829
poolSize=3,activeCount=1,completedTaskCount=1,taskCount=2,taskWaitCount=0
MyThread thread2 start 2011-12-30 19:25:22 923
poolSize=3,activeCount=2,completedTaskCount=1,taskCount=4,taskWaitCount=1
MyThread thread3 start 2011-12-30 19:25:23 033
poolSize=3,activeCount=3,completedTaskCount=1,taskCount=5,taskWaitCount=1
poolSize=3,activeCount=3,completedTaskCount=1,taskCount=6,taskWaitCount=2
poolSize=3,activeCount=3,completedTaskCount=1,taskCount=7,taskWaitCount=3
poolSize=3,activeCount=3,completedTaskCount=1,taskCount=8,taskWaitCount=4
poolSize=3,activeCount=3,completedTaskCount=1,taskCount=9,taskWaitCount=5
poolSize=4,activeCount=3,completedTaskCount=1,taskCount=9,taskWaitCount=5
MyThread thread4 start 2011-12-30 19:25:23 626
poolSize=5,activeCount=4,completedTaskCount=1,taskCount=10,taskWaitCount=5
MyThread thread5 start 2011-12-30 19:25:23 736
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$MyTask@18dfef8
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$MyTask@15e83f9
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$MyTask@2a5330
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$MyTask@bb7465
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$MyTask@d6c16c
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$

MyTask@134bed0
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$MyTask@1db4f6f
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$MyTask@13c1b02
java.util.concurrent.RejectedExecutionException,ThreadPoolTest$MyTask@11121f6
MyThread thread6 start 2011-12-30 19:25:25 829
MyThread thread7 start 2011-12-30 19:25:25 923
MyThread thread8 start 2011-12-30 19:25:26 033
MyThread thread9 start 2011-12-30 19:25:26 626
MyThread thread10 start 2011-12-30 19:25:26 736
poolSize=3,activeCount=0,completedTaskCount=11,taskCount=11,taskWaitCount=0