Java 具有ArrayBlockingQueue的ThreadPoolExecutor
在我的一个项目中使用ThreadPoolExecutor时,我开始从Java文档中阅读更多关于ThreadPoolExecutor的内容。有人能解释一下这条线的实际含义吗?-我知道每个参数代表什么,但我想从这里的一些专家那里更一般地理解它Java 具有ArrayBlockingQueue的ThreadPoolExecutor,java,multithreading,threadpool,executorservice,Java,Multithreading,Threadpool,Executorservice,在我的一个项目中使用ThreadPoolExecutor时,我开始从Java文档中阅读更多关于ThreadPoolExecutor的内容。有人能解释一下这条线的实际含义吗?-我知道每个参数代表什么,但我想从这里的一些专家那里更一般地理解它 ExecutorService service = new ThreadPoolExecutor(10, 10, 1000L, TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(10,
ExecutorService service = new ThreadPoolExecutor(10, 10, 1000L,
TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(10, true), new
ThreadPoolExecutor.CallerRunsPolicy());
ExecutorService服务=新的线程池executor(10,10,1000L,
TimeUnit.millizes,新建ArrayBlockingQueue(10,true),新建
ThreadPoolExecutor.CallerRunPolicy());
更新:-
问题陈述是:-
每个线程使用1到1000之间的唯一ID,程序必须运行60分钟或更长时间,因此在这60分钟内,所有ID都可能完成,因此我需要再次重用这些ID。这是我用上面的执行器写的下面的程序
class IdPool {
private final LinkedList<Integer> availableExistingIds = new LinkedList<Integer>();
public IdPool() {
for (int i = 1; i <= 1000; i++) {
availableExistingIds.add(i);
}
}
public synchronized Integer getExistingId() {
return availableExistingIds.removeFirst();
}
public synchronized void releaseExistingId(Integer id) {
availableExistingIds.add(id);
}
}
class ThreadNewTask implements Runnable {
private IdPool idPool;
public ThreadNewTask(IdPool idPool) {
this.idPool = idPool;
}
public void run() {
Integer id = idPool.getExistingId();
someMethod(id);
idPool.releaseExistingId(id);
}
// This method needs to be synchronized or not?
private synchronized void someMethod(Integer id) {
System.out.println("Task: " +id);
// and do other calcuations whatever you need to do in your program
}
}
public class TestingPool {
public static void main(String[] args) throws InterruptedException {
int size = 10;
int durationOfRun = 60;
IdPool idPool = new IdPool();
// create thread pool with given size
ExecutorService service = new ThreadPoolExecutor(size, size, 500L, TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(size), new ThreadPoolExecutor.CallerRunsPolicy());
// queue some tasks
long startTime = System.currentTimeMillis();
long endTime = startTime + (durationOfRun * 60 * 1000L);
// Running it for 60 minutes
while(System.currentTimeMillis() <= endTime) {
service.submit(new ThreadNewTask(idPool));
}
// wait for termination
service.shutdown();
service.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS);
}
}
类IdPool{
private final LinkedList availableExistingIds=新LinkedList();
公共IdPool(){
对于(int i=1;i它正在创建一个ExecutorService
,该服务处理线程池的执行。在这种情况下,池中的初始线程数和最大线程数都是10。当池中的线程空闲1秒(1000ms)时,它将杀死它(空闲计时器)但是,由于最大线程数和核心线程数相同,因此这种情况永远不会发生(它始终保持10个线程,并且运行的线程数永远不会超过10个)
它使用一个ArrayBlockingQueue
来管理具有10个插槽的执行请求,因此当队列已满时(在10个线程排队后),它将阻止调用者
如果线程被拒绝(在这种情况下,这可能是由于服务关闭,因为线程将排队,或者如果队列已满,在排队线程时您将被阻止),那么提供的Runnable
将在调用者的线程上执行。[首先,我很抱歉,这是对先前答案的回应,但我想要格式化]
除实际情况外,当项目提交给具有完整队列的ThreadPoolExecutor时,您不会阻止。原因是ThreadPoolExecutor调用BlockingQueue.offer(T item)方法,根据定义,该方法是非阻止方法。它要么添加项目并返回true,要么不添加(完整时)然后ThreadPoolExecutor调用注册的RejectedExecutionHandler来处理这种情况
从javadoc:
在将来某个时候执行给定的任务。该任务可能会执行
在新线程或现有池线程中。如果无法
提交执行,因为该执行人已
关闭或由于已达到其容量,任务已被处理
由当前的RejectedExecutionHandler执行
默认情况下,使用ThreadPoolExecutor.AbortPolicy()从ThreadPoolExecutor的“submit”或“execute”方法抛出RejectedExecutionException
try {
executorService.execute(new Runnable() { ... });
}
catch (RejectedExecutionException e) {
// the queue is full, and you're using the AbortPolicy as the
// RejectedExecutionHandler
}
但是,您可以使用其他处理程序执行不同的操作,例如忽略错误(DiscardPolicy),或者在调用“execute”或“submit”方法(CallerRunPolicy)的线程中运行它。此示例允许调用“submit”或“execute”方法的线程在队列已满时运行请求的任务。(这意味着在任何给定时间,您都可以在池中的内容之上运行另外一个内容):
如果您想阻塞并等待,您可以实现自己的RejectedExecutionHandler,它将阻塞直到队列上有可用的插槽(这是一个粗略的估计,我没有编译或运行它,但您应该知道):
考虑信号量。这些都是为了同样的目的。请检查下面使用信号量的代码。不确定这是否是您想要的。但如果没有更多的许可证可以获取,这将阻止。ID对您也很重要吗
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Semaphore;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
class ThreadNewTask implements Runnable {
private Semaphore idPool;
public ThreadNewTask(Semaphore idPool) {
this.idPool = idPool;
}
public void run() {
// Integer id = idPool.getExistingId();
try {
idPool.acquire();
someMethod(0);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
idPool.release();
}
// idPool.releaseExistingId(id);
}
// This method needs to be synchronized or not?
private void someMethod(Integer id) {
System.out.println("Task: " + id);
// and do other calcuations whatever you need to do in your program
}
}
public class TestingPool {
public static void main(String[] args) throws InterruptedException {
int size = 10;
int durationOfRun = 60;
Semaphore idPool = new Semaphore(100);
// IdPool idPool = new IdPool();
// create thread pool with given size
ExecutorService service = new ThreadPoolExecutor(size, size, 500L,
TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(size),
new ThreadPoolExecutor.CallerRunsPolicy());
// queue some tasks
long startTime = System.currentTimeMillis();
long endTime = startTime + (durationOfRun * 60 * 1000L);
// Running it for 60 minutes
while (System.currentTimeMillis() <= endTime) {
service.submit(new ThreadNewTask(idPool));
}
// wait for termination
service.shutdown();
service.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS);
}
}
import java.util.concurrent.ArrayBlockingQueue;
导入java.util.concurrent.ExecutorService;
导入java.util.concurrent.Semaphore;
导入java.util.concurrent.ThreadPoolExecutor;
导入java.util.concurrent.TimeUnit;
类ThreadNewTask实现可运行{
专用信号量idPool;
公共线程任务(信号量idPool){
this.idPool=idPool;
}
公开募捐{
//整数id=idPool.getExistingId();
试一试{
idPool.acquire();
方法(0);
}捕捉(中断异常e){
e、 printStackTrace();
}最后{
idPool.release();
}
//idPool.releaseExistingId(id);
}
//此方法是否需要同步?
私有方法(整数id){
System.out.println(“任务:+id”);
//在你的程序中做任何你需要做的计算
}
}
公共类测试池{
公共静态void main(字符串[]args)引发InterruptedException{
int size=10;
int durationOfRun=60;
信号量idPool=新信号量(100);
//IdPool IdPool=新的IdPool();
//创建具有给定大小的线程池
ExecutorService服务=新的线程池Executor(大小,大小,500L,
TimeUnit.ms,新的ArrayBlockingQueue(大小),
新的ThreadPoolExecutor.CallerRunPolicy());
//将一些任务排队
long startTime=System.currentTimeMillis();
长结束时间=开始时间+(运行持续时间*60*1000L);
//运行60分钟
while(System.currentTimeMillis()另一个解决方案是对底层队列进行黑客攻击,将offer
替换为offer
,并使用较大的超时时间(最多292年,可以认为是无限的)
//辅助方法
私有静态布尔interruptbleInfiniteOffer(BlockingQueue q,Runnable r){
试一试{
返回q.offer(r,Long.MAX_值,TimeUnit.NANOSECONDS);//无限==292年
}捕捉(中断异常e){
返回false;
}
}
//具有阻塞的固定大小池(而不是o)
public class BlockUntilAvailableSlot implements RejectedExecutionHandler {
public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
if (e.isTerminated() || e.isShutdown()) {
return;
}
boolean submitted = false;
while (! submitted) {
if (Thread.currentThread().isInterrupted()) {
// be a good citizen and do something nice if we were interrupted
// anywhere other than during the sleep method.
}
try {
e.execute(r);
submitted = true;
}
catch (RejectedExceptionException e) {
try {
// Sleep for a little bit, and try again.
Thread.sleep(100L);
}
catch (InterruptedException e) {
; // do you care if someone called Thread.interrupt?
// if so, do something nice here, and maybe just silently return.
}
}
}
}
}
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Semaphore;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
class ThreadNewTask implements Runnable {
private Semaphore idPool;
public ThreadNewTask(Semaphore idPool) {
this.idPool = idPool;
}
public void run() {
// Integer id = idPool.getExistingId();
try {
idPool.acquire();
someMethod(0);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
idPool.release();
}
// idPool.releaseExistingId(id);
}
// This method needs to be synchronized or not?
private void someMethod(Integer id) {
System.out.println("Task: " + id);
// and do other calcuations whatever you need to do in your program
}
}
public class TestingPool {
public static void main(String[] args) throws InterruptedException {
int size = 10;
int durationOfRun = 60;
Semaphore idPool = new Semaphore(100);
// IdPool idPool = new IdPool();
// create thread pool with given size
ExecutorService service = new ThreadPoolExecutor(size, size, 500L,
TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(size),
new ThreadPoolExecutor.CallerRunsPolicy());
// queue some tasks
long startTime = System.currentTimeMillis();
long endTime = startTime + (durationOfRun * 60 * 1000L);
// Running it for 60 minutes
while (System.currentTimeMillis() <= endTime) {
service.submit(new ThreadNewTask(idPool));
}
// wait for termination
service.shutdown();
service.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS);
}
}