producer/consumer 通过队列获取不同的数据

Question

解决了！！！谢谢

注意你放入的是什么类型的对象Queue.If你放了一个值，比如int，然后enqueue会复制一份，大家都很高兴。如果你把一个引用，比如byte[], string, enqueue 把这个引用放到队列里，那么问题就来了。如果在消费者读取之前更改此引用，则消费者将读取 changed 版本的数据。

为避免此问题，在入队后立即在 rxThread 中获取新版本的帧引用。代码：

public void rxThreadFunc()
        {
         byte[] data = new byte[datalen];//declare for the first iteration.
            int j = 0;
            while (true)
            {

                for (int i = 0; i < rxlen; i++)
                {
                    data[j] = (byte)i;
                    j++;
                    if (j >= datalen)
                    {
                        j = 0;
                        mQ.Add(data);
                        using (StreamWriter fwriter = new StreamWriter("C:\testsave\rxdata", true))
                        {
                            for (int k = 0; k < datalen; k++)
                            {
                                fwriter.Write(data[k]);
                                fwriter.Write(",");
                            }
                            fwriter.Write("\n");
                        }
                     data = new byte[datalen];//create new reference after enqueue/Add
                    }
                }

            }
        }//rxThreadFunc()

更新1 我刚刚写了另一个更简单的代码，这样每个人都可以在没有串口硬件的情况下测试它。单击按钮运行程序。我认为线程优先级会导致此问题，在不更改 rxthread 的线程优先级的情况下，dataProc 线程将获得正确的数据。但我还是不知道为什么。

rxThread.Priority=ThreadPriority.Hightest

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Collections.Concurrent;
using System.Threading;
using System.IO;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)
        {
            Thread rxThread = new Thread(rxThreadFunc);
            rxThread.Priority = ThreadPriority.Highest;//this causes problem
            rxThread.Start();
            Thread procThread = new Thread(dataProc);
            procThread.Start();
        }
        BlockingCollection<byte[]> mQ = new BlockingCollection<byte[]>();
        int datalen = 30;         
        int rxlen = 200;
        public void rxThreadFunc()
        {
            int j = 0;
            while (true)
            {
               byte[] data = new byte[datalen];//is this in the right place?
                for (int i = 0; i < rxlen; i++)
                {
                    data[j] = (byte)i;
                    j++;
                    if (j >= datalen)
                    {
                        j = 0;
                        mQ.Add(data);
                        using (StreamWriter fwriter = new StreamWriter("C:\testsave\rxdata", true))
                        {
                            for (int k = 0; k < datalen; k++)
                            {
                                fwriter.Write(data[k]);
                                fwriter.Write(",");
                            }
                            fwriter.Write("\n");
                        }
                    }
                }

            }
        }//rxThreadFunc()
        public void dataProc()
        {
            byte[] outData = new byte[datalen];
            while (true)
            {
                if (mQ.Count > 1)
                {
                    outData=mQ.Take();
                    using(StreamWriter fwriter=new StreamWriter("C:\testsave\dataProc",true))
                    {
                        for (int i = 0; i < datalen; i++)
                        {
                            fwriter.Write(outData[i]);
                            fwriter.Write(",");
                        }
                        fwriter.Write("\n");
                    }
                }
            }
        }

    }
}

描述： 我写的这个应用程序包含两个线程。 RxThread从串口接收到数据，按照header mark 0x55 0xaa排序，将后面的30个字节放入一个FrameStructclass，然后将这个FrameStruct放入Queue。 dataProcess 线程从队列中获取帧，然后将其存储到磁盘。

SerialPort=(rxbuff)=>RxThread=(rxFrame,Queue)=>dataProcess==>disk

问题： dataProcess 线程接收并保存到磁盘的数据不知何故已损坏。

尝试过： 这是我试过的，供大家参考。

我尝试了 BlockedCollection，它是自然线程安全的，而不是 Queue，它仍然不起作用。所以我想这不是队列的问题。
我尝试在FrameStruct中添加另一个成员int cnt，它在RxThread中的messageQ.Enqueue()之前自增。然后dataProcess线程就可以正确获取了。所以我认为可能是data[]有问题，但是...
但我尝试将字节数据[30]而不是 FrameStruct 放入队列中，但不起作用。
另外我觉得dataProcess收到的时间也是正确的。

5.如果我在 RxThread 中的 Monitor.Pulse() 之后放置一个 Thread.sleep(20)，问题就解决了，但我不明白为什么？？？如果换台电脑呢？

这是代码快照。

//declared:
//Queue<FrameStruct>messageQ=new Queue<FrameStruct>;
//object _LockerMQ=new object();
private void RxThread()
    {
        int bytestoread, i;
        bool f55 = false;//55 flag
        bool fs = false;//frame start flag
        int j=0;//data index in FrameStruct
        int m_lMaxFram=32;
        bytestoread = 0;
        FrameStruct rxFrame = new FrameStruct((int)m_lMaxFrame);
        while (true)
        {
            if (Serial_Port.IsOpen == true)
            {
                if ((bytestoread = Serial_Port.BytesToRead) > m_lMaxFrame*2)//get at least two frames
                {
                        rxbuff = new byte[bytestoread];  
                        Serial_Port.Read(rxbuff, 0, bytestoread);
                        for (i = 0; i < bytestoread; i++)
                        {
                            if (rxbuff[i] == 0x55)
                            {
                                f55 = true;
                                continue;
                            }
                            if (rxbuff[i] == 0xaa && f55)
                            {//frame header 0x55, 0xaa
                                //new frame start
                                fs = true;
                                f55 = false;
                                j = 0;//rxframe index;
                                rxFrame.time = DateTime.Now;//store the datetime when this thread gets this frame
                                continue;
                            }
                            if (fs && j < m_lMaxFrame - 2)
                            {//frame started but not ended
                                rxFrame.data[j] = rxbuff[i];
                                j++;
                            }
                            if (j >= (m_lMaxFrame - 2) && fs)
                            {//frame ended if j=30, reaches the end of rxFrame.data
                                fs = false;
                                lock(_LockerMQ)
                                {
                                    messageQ.Enqueue(rxFrame);
                                Monitor.Pulse(_LockerMQ);
                                }
                                 //Thread.Sleep(20);//if uncomment this sleep, problem solved
                              using (StreamWriter fWriter = new StreamWriter("c:\testsave\RXdata", true))//save rxThread result into a file rawdata
                    {
                        fWriter.Write(rxFrame.time.ToString("yyyy/MM/dd HH:mm:ss.fff"));
                        fWriter.Write(",");
                        for (int k = 0; k < m_lMaxFrame - 2; k++)
                        {
                            fWriter.Write(rxFrame.data[k]);
                            fWriter.Write(",");
                        }
                        fWriter.Write("\n");
                    }
                            }
                           }
                }//if ((bytestoread=Serial_Port.BytesToRead) > 0)
                rxbuff = null;
                Thread.Sleep(20);
            }//(Serial_Port.IsOpen==true)
            Thread.Sleep(100);
        }//while(true),RxThread sleep
    }//private void RxThread()

DataProcess 线程：

 public void dataProcess()
    {
      while (true)
        {
            lock (_LockerMQ)
            {
                while (messageQ.Count < 1) Monitor.Wait(_LockerMQ);//get at least one frame data
                f_NewFrame = messageQ.Count;
                if (f_NewFrame > 0)
                {
                    procFrame = messageQ.Dequeue();
                    using (StreamWriter fWriter = new StreamWriter("c:\testsave\dPdata", true))
                    {
                        fWriter.Write(procFrame.time.ToString("yyyy/MM/dd HH:mm:ss.fff"));
                        fWriter.Write(",");
                        for (int i = 0; i < m_lMaxFrame - 2; i++)
                        {
                            fWriter.Write(procFrame.data[i]);
                            fWriter.Write(",");
                        }
                        fWriter.Write("\n");
                    }
                }//if(f_NewFrame>0)

            }//lock(messageQ)
  }
}

FrameStruct 包含时间成员和数据[30]

class FrameStruct
{
        public FrameStruct(int m_lMaxFrame)
        {
            time = DateTime.Now;
            data = new byte[m_lMaxFrame - 2];
        }
        public DateTime time;
        public volatile byte[] data;//volatile doesn't help
}

RxThread保存的rxData是正确的，显示：

2015/07/18 18:40:26.125,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,111,51,204,
2015/07/18 18:40:26.177,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,112,51,204,
2015/07/18 18:40:26.177,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,113,51,204,
2015/07/18 18:40:26.297,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,114,51,204,
2015/07/18 18:40:26.298,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,115,51,204,
2015/07/18 18:40:26.298,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,116,51,204,
2015/07/18 18:40:26.299,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,117,51,204,
2015/07/18 18:40:26.420,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,118,51,204,
                                                                                     //^this columns is accumulated number

dataProcessThread 保存的 dPdata 是错误的，显示：

2015/07/18 18:40:31.904,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,227,51,204,
2015/07/18 18:40:31.905,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,228,51,204,
2015/07/18 18:40:31.905,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,229,51,204,
2015/07/18 18:40:32.026,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,231,51,204,
2015/07/18 18:40:32.026,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,231,51,204,
2015/07/18 18:40:32.147,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,232,51,204,
2015/07/18 18:40:32.148,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,233,51,204,
2015/07/18 18:40:32.148,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,234,51,204,
2015/07/18 18:40:32.269,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,236,51,204,
2015/07/18 18:40:32.269,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,236,51,204,
2015/07/18 18:40:32.510,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,237,51,204,
2015/07/18 18:40:32.512,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,240,51,204,
2015/07/18 18:40:32.512,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,240,51,204,
2015/07/18 18:40:32.514,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,240,51,204,
2015/07/18 18:40:32.514,127,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,241,51,204,
2015/07/18 18:40:32.635,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,243,51,204,
2015/07/18 18:40:32.635,128,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,243,51,204,
                                                                                   //^this accumulated number is not correct

请帮忙！

谢谢！

Answer 1

FrameStruct 是一个 class（而不是一个结构），当您将它排入队列时，您一遍又一遍地使用相同的引用。

Answer 2

更新 2

这是基本的生产者消费者，只需添加您的逻辑：

class Program
{

    static BlockingCollection<int> mQ = new BlockingCollection<int>();

    static void Main(string[] args)
    {

        Thread rxThread = new Thread(rxThreadFunc);
        rxThread.Priority = ThreadPriority.Highest;//this causes problem
        rxThread.Start();
        Thread procThread = new Thread(dataProc);
        procThread.Start();
        Console.ReadLine();
    }


    static public void rxThreadFunc()
    {
        for (int i = 0; i < 10; i++)
        {
            mQ.Add(i);
        }
    }


    static public void dataProc()
    {
        foreach (int outData in mQ.GetConsumingEnumerable())
        {
            Console.WriteLine(outData);
        }
    }


}

更新 1 的答案：

是的，这是在正确的地方

现在，由于您使用的 BlockingCollection，消费者 (dataProc) 可能非常简单（只需删除循环和计数检查，它会为您完成所有这些同步）：

 foreach (byte[] outData in _taskQ.GetConsumingEnumerable())
 {
     using(StreamWriter fwriter=new StreamWriter("C:\testsave\dataProc",true))
                {
                    for (int i = 0; i < datalen; i++)
                    {
                        fwriter.Write(outData[i]);
                        fwriter.Write(",");
                    }
                    fwriter.Write("\n");
                }
 }

现在，问题可能与原来的问题不同 post。也许是因为生产者在这里也将数据写入文件？

原文：

它有很多解释，但解决方案很简单，只需将 FrameStruct 的初始化添加到您的第二个 "if" 语句：

rxFrame = new FrameStruct((int)m_lMaxFrame);

如您保存的数据文件所示：在损坏的文件中，每次当您有缺失值（例如 230）时 - 您都会复制其他值（例如 231）。缺失值的计数等于重复值的计数。

原因是您将对同一对象实例的引用添加到您的队列中。让我们看看下面的场景：RxThread 循环了 N 次，在它上下文切换到 dataProcess 线程之前，它向队列中添加了对同一个 FrameStruct 实例的 N 个引用。此实例中的数据将是上下文切换之前最后一次读取循环迭代的数据。现在上下文切换发生了：dataProcess 在上下文切换回 RxThread 之前循环了 M < N 次，因此它从队列中读取 M 个元素，但所有元素都指向同一个实例，因此它在同一行中写入 M 次文件（最后一个如前所述）

现在，为什么 Thread.Sleep 有帮助。简短的回答：每次 RxThread 将 1 个元素添加到队列时，上下文切换到 dataProcess 线程的可能性非常高。所以它实际上是：读一个 --> 上下文切换 --> 写一个... 又是同样的事情。

长答案是：在 dataProcess 线程执行 Monitor.Wait 之后，它进入等待队列，上下文切换调度 RxThread。现在线程将第一个元素添加到队列中并执行 Monitor.Pulse。这会将 dataProcess 线程移动到就绪队列。但不一定立即为运行调度它，因此 RxThread 可以进行另一次迭代。但是，如果您执行 Thread.Sleep - 现在很有可能会进行上下文切换和 ataProcess 线程。

producer/consumer 通过队列获取不同的数据

producer/consumer get different data by Queue

c#

multithreading

queue

pass-by-reference

thread-priority