个人网站建设教学视频百度云盘,wordpress 公众号登录,个人网站推荐,公司域名备案网站名称作者要的是一个生产者生成#xff0c;接着必须有一个消费者消费#xff0c;那这不是需要单线程吗#xff1f;或者使用1个大小的阻塞队列。所以只谈论问题本身#xff0c;不谈论好不好。 具体代码#xff1a; Java代码 import java.util.concurrent.locks.Condition; i…作者要的是一个生产者生成接着必须有一个消费者消费那这不是需要单线程吗或者使用1个大小的阻塞队列。所以只谈论问题本身不谈论好不好。 具体代码 Java代码 import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; //生产/消费者模式 public class Basket { Lock lock new ReentrantLock(); // 产生Condition对象 Condition produced lock.newCondition(); Condition consumed lock.newCondition(); boolean available false; public void produce() throws InterruptedException { lock.lock(); try { if (available) { produced.await(); // 放弃lock进入睡眠 } System.out.println(Apple produced.); available true; consumed.signal(); // 发信号唤醒等待这个Condition的线程 } finally { lock.unlock(); } } public void consume() throws InterruptedException { lock.lock(); try { if (!available) { consumed.await(); // 放弃lock进入睡眠 } /* 吃苹果 */ System.out.println(Apple consumed.); available false; produced.signal(); // 发信号唤醒等待这个Condition的线程 } finally { lock.unlock(); } } } import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;//生产/消费者模式public class Basket {Lock lock new ReentrantLock();// 产生Condition对象Condition produced lock.newCondition();Condition consumed lock.newCondition();boolean available false;public void produce() throws InterruptedException {lock.lock();try {if (available) {produced.await(); // 放弃lock进入睡眠}System.out.println(Apple produced.);available true;consumed.signal(); // 发信号唤醒等待这个Condition的线程} finally {lock.unlock();}}public void consume() throws InterruptedException {lock.lock();try {if (!available) {consumed.await(); // 放弃lock进入睡眠}/* 吃苹果 */System.out.println(Apple consumed.);available false;produced.signal(); // 发信号唤醒等待这个Condition的线程} finally {lock.unlock();}}}Java代码 import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; //测试用类 public class ConditionTester { public static void main(String[] args) throws InterruptedException { final Basket basket new Basket(); // 定义一个producer Runnable producer new Runnable() { public void run() { try { basket.produce(); } catch (InterruptedException ex) { ex.printStackTrace(); } } }; // 定义一个consumer Runnable consumer new Runnable() { public void run() { try { basket.consume(); } catch (InterruptedException ex) { ex.printStackTrace(); } } }; // 各产生10个consumer和producer ExecutorService service Executors.newCachedThreadPool(); for (int i 0; i 4; i) service.submit(consumer); Thread.sleep(2000 * 2); for (int i 0; i 4; i) service.submit(producer); service.shutdown(); } } import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;//测试用类
public class ConditionTester {public static void main(String[] args) throws InterruptedException {final Basket basket new Basket();// 定义一个producerRunnable producer new Runnable() {public void run() {try {basket.produce();} catch (InterruptedException ex) {ex.printStackTrace();}}};// 定义一个consumerRunnable consumer new Runnable() {public void run() {try {basket.consume();} catch (InterruptedException ex) {ex.printStackTrace();}}};// 各产生10个consumer和producerExecutorService service Executors.newCachedThreadPool();for (int i 0; i 4; i)service.submit(consumer);Thread.sleep(2000 * 2);for (int i 0; i 4; i)service.submit(producer);service.shutdown();}
}原因分析 1、假设前面有2个producer(此时availabletrue) 1.1、一个在等待lock 1.2、一个await 2、consumer生成内容后availablefalseproduced.signal(); 最后lock.unlock(); 3.1、因为lock.unlock所以会触发一个lock获取到锁虽然signal也会触发等待这个条件的其他线程但是多线程大家都知道什么时候触发这是不确定的如果此时正好是[1.1]那么因为availablefalse执行完释放锁 3.2、produced.signal()所以会触发一个await的producer 解决方案 只要保证[3.1]还是需要await即可解决问题 所以加一个 AtomicInteger producedAwaitCounter new AtomicInteger(0); 统计当前等待的生产者如果当前availablefalse但已经有生产者生成了内容那么先等待消费者消费了再说 if (available || producedAwaitCounter.get() 0) { producedAwaitCounter.incrementAndGet(); produced.await(); // 放弃lock进入睡眠 producedAwaitCounter.decrementAndGet(); } 当然最简单的是使用自旋原理可以自己分析下 while (available) { produced.await(); // 放弃lock进入睡眠 } Java代码 package com.sishuok.es.test; import java.util.concurrent.atomic.AtomicInteger; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; //生产/消费者模式 public class Basket { Lock lock new ReentrantLock(true); // 产生Condition对象 Condition produced lock.newCondition(); Condition consumed lock.newCondition(); boolean available false; AtomicInteger producedAwaitCounter new AtomicInteger(0); public void produce() throws InterruptedException { lock.lock(); try { if (available || producedAwaitCounter.get() 0) { producedAwaitCounter.incrementAndGet(); produced.await(); // 放弃lock进入睡眠 producedAwaitCounter.decrementAndGet(); } System.out.println(Apple produced.); available true; consumed.signal(); // 发信号唤醒等待这个Condition的线程 } finally { lock.unlock(); } } public void consume() throws InterruptedException { lock.lock(); try { if (!available) { consumed.await(); // 放弃lock进入睡眠 } /* 吃苹果 */ System.out.println(Apple consumed.); available false; produced.signal(); // 发信号唤醒等待这个Condition的线程 } finally { lock.unlock(); } } } package com.sishuok.es.test;import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;//生产/消费者模式public class Basket {Lock lock new ReentrantLock(true);// 产生Condition对象Condition produced lock.newCondition();Condition consumed lock.newCondition();boolean available false;AtomicInteger producedAwaitCounter new AtomicInteger(0);public void produce() throws InterruptedException {lock.lock();try {if (available || producedAwaitCounter.get() 0) {producedAwaitCounter.incrementAndGet();produced.await(); // 放弃lock进入睡眠producedAwaitCounter.decrementAndGet();}System.out.println(Apple produced.);available true;consumed.signal(); // 发信号唤醒等待这个Condition的线程} finally {lock.unlock();}}public void consume() throws InterruptedException {lock.lock();try {if (!available) {consumed.await(); // 放弃lock进入睡眠}/* 吃苹果 */System.out.println(Apple consumed.);available false;produced.signal(); // 发信号唤醒等待这个Condition的线程} finally {lock.unlock();}}}
