生产环境者/消费者通过Queue获取不同的数据-Java 学习之路

Solved!!! Thank you

请注意你在Queue中放入了什么样的对象 . 如果你输入一个值，比如int，那么enqueue会复制一下，每个人都很高兴 . 如果你把一个引用，比如byte []，string，enqueue把这个引用放到队列中，那么问题就来了 . 如果在消费者阅读之前更改了此引用，则使用者将读取 changed 版本的数据 .

为了避免这个问题，在rxThread中排队之后 get a new version of frame reference . 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()

Update1 我刚刚写了另一个更简单的代码，所以每个人都可以在没有serialport硬件的情况下测试它 . 单击按钮以运行程序 . 我认为线程优先级会导致这个问题，而不会改变rxthread 's thread priority the dataProc thread will get right data. but I still don'知道原因 .

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");
                    }
                }
            }
        }

    }
}

Description: 我写这个包含两个线程的应用程序 . RxThread从串口接收数据，按 Headers 0x55 0xaa排序，将以下30个字节放入FrameStruct类，然后将此FrameStruct放入Queue . dataProcess线程从Queue获取帧，然后将其存储到磁盘 .

的SerialPort =（RXBUFF）=> RxThread =（rxFrame，队列）=> dataProcess ==>磁盘

Problem: dataProcess线程接收并保存到磁盘中的数据以某种方式损坏 .

Tried: 这是我试过的参考资料 .

我尝试过BlockedCollection，它自然是线程安全而不是Queue，它仍然没有问题 .
我试图在FrameStruct中添加另一个成员int cnt，它在RxThread中的messageQ.Enqueue（）之前自行增加 . 然后dataProcess线程可以正确地获取它 . 所以我认为可能是数据[]出了问题，但......
但我试图将字节数据[30]而不是FrameStruct放入队列，不起作用 .
另外我认为dataProcess收到的时间也是正确的 .

5. If I put a Thread.sleep(20) after Monitor.Pulse() in RxThread, problem solved, but I don't understand why??? And what if I changed to another computer?

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
}

由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

由dataProcessThread保存的dPdata为WRONG，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！

2 回答

0
Update 2

这是基本的生产环境者消费者，只需添加你的逻辑：
```
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);
        }
    }


}
```
Answer for Update 1:
- 是的，这是正确的地方
现在，由于您正在使用的BlockingCollection，使用者（dataProc）可能非常简单（只需删除循环和计数检查，它将为您执行所有这些同步）：
```
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，问题可能与原帖不同 . 也许是因为这里生产环境者也将数据写入文件？

Original:

它有很多解释，但解决方案很简单，只需将FrameStruct的初始化添加到第二个“if”语句中：
```
rxFrame = new FrameStruct((int)m_lMaxFrame);
```
如您保存的数据文件中所示：在损坏的文件中，每次缺少值时（例如230） - 您都有其他值重复（例如231） . 缺失值的计数等于重复值的计数 .

原因是您将同一对象实例的引用添加到队列中 . 让我们看看下面的场景：RxThread循环N次，在上下文切换到dataProcess线程之前，它将N个参考添加到队列的同一个FrameStruct实例 . 此实例中的数据将是上下文切换之前的最后一次读取循环迭代的数据 . 现在发生了上下文切换：dataProcess在上下文切换回RxThread之前循环M <N次，因此它从队列中读取M个元素，但是所有这些元素都指向同一个实例，因此它将M次相同的行写入文件（最后一个如前所述）

现在，为什么Thread.Sleep会有所帮助 . 简短的回答：每次通过RxThread将1个元素添加到队列时，上下文切换到dataProcess线程的概率非常高 . 所以它实际上是：读一个 - >上下文切换 - >写一个......再一样 .

长的答案是：在dataProcess线程执行Monitor.Wait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 . 但不一定要安排它立即运行，因此RxThread可以进行另一次迭代 . 但是，如果你执行Thread.Sleep - 现在将安排上下文切换和ataProcess线程的概率非常高 .
回复于 2024-05-07T03:13:53+08:00
0

FrameStruct是一个类（而不是结构），并且您反复使用相同的引用当你排队的时候 .

回复于 2024-05-07T03:13:53+08:00

生产环境 者/消费者通过Queue获取不同的数据

2 回答

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生产环境者/消费者通过Queue获取不同的数据