Why does C# thread die?
- by JackN
This is my 1st C# project so I may be doing something obviously improper in the code below.
I am using .NET, WinForms (I think), and this is a desktop application until I get the bugs out.
UpdateGui() uses Invoke((MethodInvoker)delegate to update various GUI controls based on received serial data and
sends a GetStatus() command out the serial port 4 times a second.
Thread Read() reads the response from serial port whenever it arrives which should be near immediate.
SerialPortFixer is a SerialPort IOException Workaround in C# I found at
http://zachsaw.blogspot.com/2010/07/serialport-ioexception-workaround-in-c.html.
After one or both threads die I'll see something like
The thread 0x1288 has exited with code 0 (0x0).
in the debug code output.
Why do UpdateGui() and/or Read() eventually die?
public partial class UpdateStatus : Form
{
private readonly byte[] Command = new byte[32];
private readonly byte[] Status = new byte[32];
readonly Thread readThread;
private static readonly Mutex commandMutex = new Mutex();
private static readonly Mutex statusMutex = new Mutex();
...
public UpdateStatus()
{
InitializeComponent();
SerialPortFixer.Execute("COM2");
if (serialPort1.IsOpen)
{
serialPort1.Close();
}
try
{
serialPort1.Open();
}
catch (Exception e)
{
labelWarning.Text = LOST_COMMUNICATIONS + e;
labelStatus.Text = LOST_COMMUNICATIONS + e;
labelWarning.Visible = true;
}
readThread = new Thread(Read);
readThread.Start();
new Timer(UpdateGui, null, 0, 250);
}
static void ProcessStatus(byte[] status)
{
Status.State = (State) status[4];
Status.Speed = status[6]; // MSB
Status.Speed *= 256;
Status.Speed += status[5];
var Speed = Status.Speed/GEAR_RATIO;
Status.Speed = (int) Speed;
...
}
public void Read()
{
while (serialPort1 != null)
{
try
{
serialPort1.Read(Status, 0, 1);
if (Status[0] != StartCharacter[0]) continue;
serialPort1.Read(Status, 1, 1);
if (Status[1] != StartCharacter[1]) continue;
serialPort1.Read(Status, 2, 1);
if (Status[2] != (int)Command.GetStatus) continue;
serialPort1.Read(Status, 3, 1);
...
statusMutex.WaitOne();
ProcessStatus(Status);
Status.update = true;
statusMutex.ReleaseMutex();
}
catch (Exception e)
{
Console.WriteLine(@"ERROR! Read() " + e);
}
}
}
public void GetStatus()
{
const int parameterLength = 0; // For GetStatus
statusMutex.WaitOne();
Status.update = false;
statusMutex.ReleaseMutex();
commandMutex.WaitOne();
if (!SendCommand(Command.GetStatus, parameterLength))
{
Console.WriteLine(@"ERROR! SendCommand(GetStatus)");
}
commandMutex.ReleaseMutex();
}
private void UpdateGui(object x)
{
try
{
Invoke((MethodInvoker)delegate
{
Text = DateTime.Now.ToLongTimeString();
statusMutex.WaitOne();
if (Status.update)
{
if (Status.Speed > progressBarSpeed.Maximum)
{
Status.Speed = progressBarSpeed.Maximum;
}
progressBarSpeed.Value = Status.Speed;
labelSpeed.Text = Status.Speed + RPM;
...
}
else
{
labelWarning.Text = LOST_COMMUNICATIONS;
labelStatus.Text = LOST_COMMUNICATIONS;
labelWarning.Visible = true;
}
statusMutex.ReleaseMutex();
GetStatus();
});
}
catch (Exception e)
{
Console.WriteLine(@"ERROR! UpdateGui() " + e);
}
}
}
