基于C#实现的多生产者多消费者同步问题实例

// 多个生产者和多个消费者，能生产n个产品的情况

using System;
using System.Threading;

public class HoldIntegerSynchronized{
 private int[] buffer; //缓冲区
 private int occupiedBufferCount = 0;
 private int readPosition = 0 , writePosition = 0;
 //下一个读到的位置和写到的位置
 public HoldIntegerSynchronized(int capacity){
 buffer = new int[capacity];
 }
 
 public int BufferSize{
 get{
  return buffer.Length;
 }
 }

 public int Buffer{
 get{
  int bufferCopy;
  // 加锁
  lock(this){
  while(occupiedBufferCount == 0){ //多个消费者，所以此处改用while
   Console.WriteLine(Thread.CurrentThread.Name + " tries to read. ");
   DisplayState("Buffer Empty. " + Thread.CurrentThread.Name + " waits.");
   Monitor.Wait(this); 
   // 为临界区之外等待的生产者放行，让他来"生产"
   // 一直到生产者生产结束，调用了Monitor.PauseAll()
   // 才能继续执行下去,此时，消费者自动重新获得this的锁
  }
  --occupiedBufferCount;
  bufferCopy = buffer[readPosition];
  readPosition = (readPosition + 1) % buffer.Length;  
  DisplayState(Thread.CurrentThread.Name + " reads " + bufferCopy);

  // 通知，让等待的 生产者线程 进入Started状态,如果生产者处于临界区之外，这句话执行完后他仍然在临界区之外
  Monitor.PulseAll(this);

  // 释放锁
  }//lock
  return bufferCopy;
 }

 set{
  // 加锁
  lock(this){
  while(occupiedBufferCount == buffer.Length){
   Console.WriteLine(Thread.CurrentThread.Name + " tries to write. ");
   DisplayState("Buffer Full. " + Thread.CurrentThread.Name + " waits.");
   Monitor.Wait(this); 
   // 为临界区之外等待消费者放行，让他来"消费"
   // 一直到消费者调用了Monitor.Pause()
   // 才能继续执行下去，此时，生产者自动重新获得this的锁
  }

  buffer[writePosition] = value;
  ++occupiedBufferCount; 
  writePosition = (writePosition + 1) % buffer.Length;
  DisplayState(Thread.CurrentThread.Name + " writes " + value);

  // 通知，让Wait状态的 消费者 进入Started状态,如果消费者处于临界区之外，这句话执行完后他仍然在临界区之外
  Monitor.PulseAll(this);
  // 释放锁
  }
 }
 }

 public void DisplayState(string operation){
 Console.Write("{0,-35}",operation);
 for(int i = 0; i < BufferSize; i++ ){
  int a = readPosition;
  int b = writePosition;
  if( a <= i && i < b) {
  Console.Write("{0,-9}",buffer[i]);
  }else if( b < a && !( b <= i && i < a ) ){
  Console.Write("{0,-9}",buffer[i]);
  }else if( occupiedBufferCount == BufferSize){
  Console.Write("{0,-9}",buffer[i]);
  }else{
  Console.Write("{0,-9}","");
  }
 }
 Console.WriteLine("{0}/r/n",occupiedBufferCount);
 }
}

class Producer{
 private HoldIntegerSynchronized sharedLocation;
 private Random randomSleepTime;

 public Producer(HoldIntegerSynchronized shared,Random random){
 sharedLocation = shared;
 randomSleepTime = random;
 }
 
 public void Produce(){
 for (int count=0; count<3; count++) {
  Thread.Sleep(randomSleepTime.Next(1,2000));
  sharedLocation.Buffer = randomSleepTime.Next(5,10);
 }
 Console.WriteLine(Thread.CurrentThread.Name + " done producing./r/nTerminating " + Thread.CurrentThread.Name + "./r/n");
 }
}

class Consumer{
 private HoldIntegerSynchronized sharedLocation;
 private Random randomSleepTime;

 public Consumer(HoldIntegerSynchronized shared,Random random){
 sharedLocation = shared;
 randomSleepTime = random;
 }
 public void Consume(){
 int sum = 0;
 for (int count=0; count<4; count++) {
  Thread.Sleep(randomSleepTime.Next(1,2000));
  sum += sharedLocation.Buffer;
 }
 Console.WriteLine(Thread.CurrentThread.Name + " read values totaling:" + sum + "/r/nTerminating " + Thread.CurrentThread.Name + ".");
 } 
}

class SharedCell{
 static void Main(string[] args){
 HoldIntegerSynchronized holdInteger = new HoldIntegerSynchronized(5);
 Random random = new Random();
 Thread[] producerThreads = new Thread[4];
 Thread[] consumerThreads = new Thread[3];

 Console.Write("{0,-35}","Operation");
 for(int i = 0;i < holdInteger.BufferSize;i++){
  Console.Write("{0,-9}","Elem " + i);
 }
 Console.WriteLine("Occupied Count/r/n");

 for(int i = 0; i < producerThreads.Length;i++){
  Producer producer = new Producer(holdInteger,random);
  producerThreads[i] = new Thread(new ThreadStart(producer.Produce));
  producerThreads[i].Name = "Producer No." + i;
 }

 for(int i = 0; i < consumerThreads.Length;i++){
  Consumer consumer = new Consumer(holdInteger,random);
  consumerThreads[i] = new Thread(new ThreadStart(consumer.Consume));
  consumerThreads[i].Name = "Consumer No." + i;
 }

 for(int i = 0; i < producerThreads.Length;i++){
  producerThreads[i].Start();
 }

 for(int i = 0; i < consumerThreads.Length;i++){
  consumerThreads[i].Start();
 }
 }
}