EF在表中插入值时，过了一段时间就失败了。

Question

我正在努力 EF. 我试图插入一个表，插入函数是在一个线程中。

private void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e)
{
    int bytes = port.BytesToRead;
    //string indata = sp.ReadExisting();

    Thread.Sleep(50);

    try
    {
        receivedBytes = port.BaseStream.Read(buffer, 0, (int)buffer.Length);
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message.ToString());
    }

    var receiveData = BitConverter.ToString(buffer, 0, receivedBytes);
    var finalData = receiveData.Replace("-", "");
    //Thread.Sleep(100);

    Console.WriteLine("Thread Going to Start");

    new Thread(() => {
            SaveData(finalData);
        }).Start(); // starting the thread

    port.DiscardOutBuffer(); 
    port.DiscardInBuffer();
}

而这是我的保存数据函数

public void SaveData(string finalData)
{
    Console.WriteLine(LineNumber() + "Data Transmiting...");
    thread = Thread.CurrentThread;         


mdc_dbEntities e = new mdc_dbEntities();

            var msn = e.mdc_meter_config.Where(m => m.m_hex == sr).Select(s => new { s.msn, s.p_id, s.meter_id }).ToList();

    var H = finalData.Substring(0, 2);

    using (mdc_dbEntities u = new mdc_dbEntities())
    {
        foreach (var res in msn)
        {
            var cust_id = e.mdc_meter_cust_rel.Where(m => m.msn == res.msn)
                                              .Select(s => s.cust_id)
                                              .FirstOrDefault();

            mdc_meters_data data = new mdc_meters_data()
                    {
                        msn = res.msn,
                        cust_id = cust_id,
                        device_id = res.meter_id.ToString(),
                        kwh = e_val.ToString(),
                        voltage_p1 = a_vol_val.ToString(),
                        voltage_p2 = b_vol_val.ToString(),
                        voltage_p3 = c_vol_val.ToString(),
                        current_p1 = a_curr_val.ToString(),
                        current_p2 = b_curr_val.ToString(),
                        current_p3 = c_curr_val.ToString(),
                        data_date_time = Convert.ToDateTime(theDate.ToString(format)),
                        d_type = d_type.ToString(),
                        pf1 = a_pf_val.ToString(),
                        pf2 = b_pf_val.ToString(),
                        pf3 = c_pf_val.ToString(),
                        p_id = res.p_id,
                    };
            u.mdc_meters_data.Add(data);
        }

        u.SaveChanges();
    }

    Console.WriteLine(LineNumber() + "Data Saved");
    Thread.Sleep(50);
}

try
{
    thread.Abort(); // aborting it after insertion
    //Thread.Sleep(50);
}
catch (Exception ex)
{
    Console.WriteLine(ex.Message.ToString());
}
}

上面的代码运行了一段时间，但之后我遇到了一个错误，在 u.SaveChanges();

System.Data.Entity.Core.EntityException：'关闭提供者连接时发生错误。请参阅内部异常了解详情。

MySqlException: 命令执行过程中遇到致命错误。 MySqlException.Core.EntityException：'在试图关闭提供者连接时遇到致命错误。试图读取结果集时遇到致命错误。 MySqlException: MySqlException: Fatal error encountered Fatal error attempting to read the resultset: 从流中读取失败。

IOException：无法从传输连接中读取数据。无法从传输连接中读取数据。连接尝试失败，因为连接方在一段时间后没有正确响应，或者建立的连接失败，因为连接的主机没有响应。

套接字异常（SocketException）。连接尝试失败，因为连接方在一段时间后没有正确响应，或建立的连接失败，因为连接的主机没有响应。

我已经研究了每一个解决方案，并尝试了它们，但仍然无法解决这个问题。我一定是漏掉了什么我不知道的东西。

更新1 我的整个代码

调用构造函数

  public CommunicationEngine()
    {
        port.ReadTimeout = 500;
        port.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
        port.Open();

        Console.WriteLine("Port opened successfully");

        Console.WriteLine("I am Recieving");
    }

调用处理程序

 private void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e)
    {

        int bytes = port.BytesToRead;


        Thread.Sleep(50);
        Console.WriteLine("Bytes are ok..." + port.BytesToRead + " Recieved ");
        try
        {
            receivedBytes = port.BaseStream.Read(buffer, 0, (int)buffer.Length);

        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message.ToString());
        }


        var receiveData = BitConverter.ToString(buffer, 0, receivedBytes);
        var finalData = receiveData.Replace("-", "");
        //Thread.Sleep(100);

        Console.WriteLine("Thread Going to Start");

        try
        {
            new Thread(() => {
                SaveData(finalData);
            }).Start();
        }
        catch(Exception ex)
        {
            Console.WriteLine(ex.Message.ToString());
        }          


        port.DiscardOutBuffer(); port.DiscardInBuffer();



    }

将数据保存到数据库中

public void SaveData(string finalData)
    {

        Console.WriteLine(LineNumber() + "Data Transmiting...");
        thread = Thread.CurrentThread;

        if (finalData.Length == 138)
        {
            comm = true;

            var H = finalData.Substring(0, 2);

            var FC = finalData.Substring(2, 9);

            var len = finalData.Substring(10, 2);

            var sr = finalData.Substring(12, 12);

            var energy_tag = finalData.Substring(24, 4);

            var e_val = hexToDec(finalData.Substring(28, 8)) / 10;

            var a_curr_tag = finalData.Substring(36, 4);

            var a_curr_val = hexToDec(finalData.Substring(40, 8)) / 1000;

            var b_curr_tag = finalData.Substring(48, 4);

            var b_curr_val = hexToDec(finalData.Substring(52, 8)) / 1000;

            var c_curr_tag = finalData.Substring(60, 4);

            var c_curr_val = hexToDec(finalData.Substring(64, 8)) / 1000;

            var a_vol_tag = finalData.Substring(72, 4);

            var a_vol_val = hexToDec(finalData.Substring(76, 8)) / 10;

            var b_vol_tag = finalData.Substring(84, 4);

            var b_vol_val = hexToDec(finalData.Substring(88, 8)) / 10;

            var c_vol_tag = finalData.Substring(96, 4);

            var c_vol_val = hexToDec(finalData.Substring(100, 8)) / 10;

            var a_pf_tag = finalData.Substring(108, 4);

            var a_pf_val = hexToDec(finalData.Substring(112, 4)) / 1000;

            var b_pf_tag = finalData.Substring(116, 4);

            var b_pf_val = hexToDec(finalData.Substring(120, 4)) / 1000;

            var c_pf_tag = finalData.Substring(124, 4);

            var c_pf_val = hexToDec(finalData.Substring(128, 4)) / 1000;

            var crc = finalData.Substring(132, 4);

            var ftr = finalData.Substring(136, 2);


            var d_type = "600";

            DateTime theDate = DateTime.Now;

            string format = "yyyy-MM-dd HH:mm:ss";
            Console.WriteLine(LineNumber() + "Data Ready to be inserted in DB");
            using (mdc_dbEntities u = new mdc_dbEntities())
            {
                var msnList = u.mdc_meter_config.Where(m => m.m_hex == sr)
                .Select(s => new { s.msn, s.p_id, s.meter_id })
                .ToList();

                foreach (var res in msnList)
                {
                    var cust_id = u.mdc_meter_cust_rel.Where(m => m.msn == res.msn)
                        .Select(s => s.cust_id)
                        .FirstOrDefault();

                    mdc_meters_data data = new mdc_meters_data()
                    {
                        msn = res.msn,
                        cust_id = cust_id,
                        device_id = res.meter_id.ToString(),
                        kwh = e_val.ToString(),
                        voltage_p1 = a_vol_val.ToString(),
                        voltage_p2 = b_vol_val.ToString(),
                        voltage_p3 = c_vol_val.ToString(),
                        current_p1 = a_curr_val.ToString(),
                        current_p2 = b_curr_val.ToString(),
                        current_p3 = c_curr_val.ToString(),
                        data_date_time = Convert.ToDateTime(theDate.ToString(format)),
                        d_type = d_type.ToString(),
                        pf1 = a_pf_val.ToString(),
                        pf2 = b_pf_val.ToString(),
                        pf3 = c_pf_val.ToString(),
                        p_id = res.p_id,
                    };
                    u.mdc_meters_data.Add(data);

                }
                try
                {
                    u.SaveChanges();
                }
                catch(Exception ex)
                {
                    Console.WriteLine(ex.Message.ToString());
                }

            }                

            Console.WriteLine(LineNumber() + "Data Saved");
            Thread.Sleep(50);

        }
        else if(finalData.Length == 30)
        {
            var msn_no = finalData.Substring(12, 12);

            mdc_dbEntities p = new mdc_dbEntities();

            var update = p.meter_control.Where(c => (c.comm_executed == 0))
                          .Where(o => (o.m_hex == msn_no))
                          .SingleOrDefault();

            if(update.comm_sent == "Disconnect")
            {
                update.comm_executed = 1;
                update.comm = 0;
                p.SaveChanges();
                Console.WriteLine("Meter Disconnected....");
            }
            else if(update.comm_sent == "Connect")
            {

                update.comm_executed = 1;
                update.comm = 1;
                p.SaveChanges();
                Console.WriteLine("Meter Connected....");
            }             

            comm = true;
        }
        else
        {
            comm = true;
        }

        try
        {
            thread.Abort();

        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message.ToString());
        }

    }

任何帮助将被高度赞赏。

Answer 1

在手动启动的线程中执行EF相关的变化不是一个好主意。试着在同一个线程中运行EF的变化。如果你为处理传入的请求而烦恼，请使用Async，和Await功能。我已经修改了你的代码来适应这个功能。请试试这个。

private void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e)
{
    int bytes = port.BytesToRead;
    //string indata = sp.ReadExisting();

    try
    {
        receivedBytes = port.BaseStream.Read(buffer, 0, (int)buffer.Length);
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message.ToString());
    }

    var receiveData = BitConverter.ToString(buffer, 0, receivedBytes);
    var finalData = receiveData.Replace("-", "");

    Console.WriteLine("Thread Going to Start");

    SaveDataAsync(finalData).Wait(); // this call will become sync and runs under main thread.

    port.DiscardOutBuffer(); 
    port.DiscardInBuffer();
}

public async Task<bool> SaveDataAsync(string finalData)
{
mdc_dbEntities e = new mdc_dbEntities();

            var msn = e.mdc_meter_config.Where(m => m.m_hex == sr).Select(s => new { s.msn, s.p_id, s.meter_id }).ToList();

    var H = finalData.Substring(0, 2);
var isSaveSuccess = false;
    using (mdc_dbEntities u = new mdc_dbEntities())
    {
        foreach (var res in msn)
        {
            var cust_id = e.mdc_meter_cust_rel.Where(m => m.msn == res.msn)
                                              .Select(s => s.cust_id)
                                              .FirstOrDefault();

            mdc_meters_data data = new mdc_meters_data()
                    {
                        msn = res.msn,
                        cust_id = cust_id,
                        device_id = res.meter_id.ToString(),
                        kwh = e_val.ToString(),
                        voltage_p1 = a_vol_val.ToString(),
                        voltage_p2 = b_vol_val.ToString(),
                        voltage_p3 = c_vol_val.ToString(),
                        current_p1 = a_curr_val.ToString(),
                        current_p2 = b_curr_val.ToString(),
                        current_p3 = c_curr_val.ToString(),
                        data_date_time = Convert.ToDateTime(theDate.ToString(format)),
                        d_type = d_type.ToString(),
                        pf1 = a_pf_val.ToString(),
                        pf2 = b_pf_val.ToString(),
                        pf3 = c_pf_val.ToString(),
                        p_id = res.p_id,
                    };
            u.mdc_meters_data.Add(data);
        }

       isSaveSuccess = (await u.SaveChangesAsync())>0; // if records inserted, the count will be more than 0
    }

   return isSaveSuccess;
}

}

Answer 2

这是更容易阅读和可能帮助

说了这么多，请确保你能真正连接到dbdouble检查连接字符串。

public void SaveData(string finalData)
{
    Console.WriteLine(LineNumber() + "Data Transmiting...");

    using (mdc_dbEntities dbContext = new mdc_dbEntities())
    {
        var msnList = dbContext.mdc_meter_config.Where(m => m.m_hex == sr)
                    .Select(s => new { s.msn, s.p_id, s.meter_id })
                    .ToList();

        //put debug point here and check that msnList is populated
        foreach (var item in msnList)
        {
            //this is slow as it will be a db query for each loop
            var cust_id = dbContext.mdc_meter_cust_rel.Where(m => m.msn == item.msn)
                                   .Select(s => s.cust_id)
                                   .FirstOrDefault();

            var data = new mdc_meters_data()
            {
                msn = item.msn,
                cust_id = cust_id,
                device_id = item.meter_id.ToString(),
                kwh = e_val.ToString(),
                voltage_p1 = a_vol_val.ToString(),
                voltage_p2 = b_vol_val.ToString(),
                voltage_p3 = c_vol_val.ToString(),
                current_p1 = a_curr_val.ToString(),
                current_p2 = b_curr_val.ToString(),
                current_p3 = c_curr_val.ToString(),
                data_date_time = Convert.ToDateTime(theDate.ToString(format)),
                d_type = d_type.ToString(),
                pf1 = a_pf_val.ToString(),
                pf2 = b_pf_val.ToString(),
                pf3 = c_pf_val.ToString(),
                p_id = item.p_id,
            };
            dbContext.mdc_meters_data.Add(data);
        }

        //depending on how many you added this may take some time.
        dbContext.SaveChanges();
    }
}