Java中的多个消费者生产者
我尝试为消费者创建 2 个线程，为生产者创建 2 个线程。所有 4 个线程都在与一种资源竞争。其中两个试图从资源中消费，其中两个试图生产。
下面是代码
package com.threading;
import java.util.ArrayList;
import java.util.List;
public class TestConsumerProducer2 {
protected static int maxSize = 2;
static class Consumer implements Runnable {
List<Integer> goods;
public Consumer(List<Integer> goods) {
this.goods = goods;
}
public void consume() {
synchronized (goods) {
if (goods.size() <= 0) {
try {
goods.wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
System.out.println(Thread.currentThread().getName() + " >>>> consuming >>>" + goods.remove(0));
goods.notifyAll();
}
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
consume();
try {
Thread.currentThread().sleep(100);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
static class Producer implements Runnable {
List<Integer> goods;
public Producer(List<Integer> goods) {
this.goods = goods;
}
public void produce(int i) {
synchronized (goods) {
if (goods.size() >= maxSize) {
try {
goods.wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
System.out.println(Thread.currentThread().getName() + ">>> producing >> " + i);
goods.add(i);
goods.notifyAll();
}
}
慕哥92293981回答
-
千巷猫影
更改代码中出现的iftowhile可以解决问题。Oracle 网站上的Guarded Blocks 教程中有相关建议，其中说：注意：始终在测试等待条件的循环内调用 wait。不要假设中断是针对您正在等待的特定条件，或者条件仍然为真。（中断是指从等待中返回，不一定是来自调用 Thread.interrupt 的人的实际中断。）关键点：只有当线程在检查时持有锁时，它才知道货物列表的内容。调用 wait 会放弃锁，允许其他线程在这个线程处于休眠状态时取得进展。一旦线程放弃锁，它之前对货物列表状态所做的任何检查都不再有效。一旦线程从等待中返回，它就重新获得了锁，但该线程需要重新评估条件检查，否则它正在处理陈旧的信息。在线程上次检查条件的时间和当前时间之间可能发生了很多事情。您得到 IllegalArgumentException 是因为当前线程假设在当前线程等待时另一个线程删除了某些东西。package com.threading;import java.util.ArrayList; import java.util.List;public class TestConsumerProducer2 {protected static int maxSize = 2;static class Consumer implements Runnable { List<Integer> goods; public Consumer(List<Integer> goods) { this.goods = goods; } public void consume() { synchronized (goods) { while (goods.size() <= 0) { try { goods.wait(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } System.out.println(Thread.currentThread().getName() + " >>>> consuming >>>" + goods.remove(0)); goods.notifyAll(); } } @Override public void run() { for (int i = 0; i < 10; i++) { consume(); try { Thread.currentThread().sleep(100); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }}static class Producer implements Runnable { List<Integer> goods; public Producer(List<Integer> goods) { this.goods = goods; } public void produce(int i) { synchronized (goods) { while (goods.size() >= maxSize) { try { goods.wait(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } System.out.println(Thread.currentThread().getName() + ">>> producing >> " + i); goods.add(i); goods.notifyAll(); } } @Override public void run() { // TODO Auto-generated method stub for (int i = 0; i < 10; i++) { produce(i); try { Thread.currentThread().sleep(100); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }}public static void main(String[] args) { List<Integer> goods = new ArrayList<>(); Consumer consumer = new Consumer(goods); Producer producer = new Producer(goods); Thread consumerWorker1 = new Thread(consumer); Thread consumerWorker2 = new Thread(consumer); Thread prroducerWorker1 = new Thread(producer); Thread prroducerWorker2 = new Thread(producer); consumerWorker1.start(); consumerWorker2.start(); prroducerWorker1.start(); prroducerWorker2.start(); try { consumerWorker1.join(); consumerWorker2.join(); prroducerWorker1.join(); prroducerWorker2.join(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println("Job completed >>>>");}}代码现在成功完成，输出如下：C:\>java com.threading.TestConsumerProducer2Thread-2>>> producing >> 0Thread-1 >>>> consuming >>>0Thread-3>>> producing >> 0Thread-0 >>>> consuming >>>0Thread-2>>> producing >> 1Thread-3>>> producing >> 1Thread-0 >>>> consuming >>>1Thread-1 >>>> consuming >>>1Thread-2>>> producing >> 2Thread-3>>> producing >> 2Thread-0 >>>> consuming >>>2Thread-1 >>>> consuming >>>2Thread-2>>> producing >> 3Thread-0 >>>> consuming >>>3Thread-3>>> producing >> 3Thread-1 >>>> consuming >>>3Thread-2>>> producing >> 4Thread-0 >>>> consuming >>>4Thread-3>>> producing >> 4Thread-1 >>>> consuming >>>4Thread-2>>> producing >> 5Thread-0 >>>> consuming >>>5Thread-3>>> producing >> 5Thread-1 >>>> consuming >>>5Thread-2>>> producing >> 6Thread-0 >>>> consuming >>>6Thread-3>>> producing >> 6Thread-1 >>>> consuming >>>6Thread-2>>> producing >> 7Thread-0 >>>> consuming >>>7Thread-3>>> producing >> 7Thread-1 >>>> consuming >>>7Thread-2>>> producing >> 8Thread-0 >>>> consuming >>>8Thread-3>>> producing >> 8Thread-1 >>>> consuming >>>8Thread-2>>> producing >> 9Thread-0 >>>> consuming >>>9Thread-3>>> producing >> 9Thread-1 >>>> consuming >>>9Job completed >>>>
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Java