Finally solution for everything described below is to install DotNet v4.5 on computers where my application is running, even though my application was developed and designed for DotNet v4.0
I am facing memory leak when COM to USB converter unplugged from computer. Memory dump shows me that I have hundreds of new System.Threading.OverlappedData object.
Type System.Threading.OverlappedData
New objects 246368
New bytes 16753024
Dead bytes 0
Bytes delta 16753024
Type System.IO.Ports.SerialStream+SerialStreamAsyncResult
New objects 246353
New bytes 9854120
Dead bytes 0
Bytes delta 9854120
Type System.Threading._IOCompletionCallback
New objects 246352
New bytes 6897856
Dead bytes 0
Bytes delta 6897856
My test application just opens port and has no event listeners. using System;
using System.IO.Ports;
using System.Text;
namespace OpenSerialPortApp
{
class Program
{
static void Main(string[] args)
{
var Sp = new SerialPort
{
StopBits = StopBits.One,
BaudRate = 9600,
DataBits = 8,
Parity = Parity.None,
Encoding = Encoding.UTF8,
PortName = "COM5"
};
Console.WriteLine("Port Created");
Sp.Open();
Console.WriteLine("Port started");
//No I just unplug my COM to USB converter.
Console.ReadKey();
}
}
}
I tried to Close and Dispose serial port when it becomes unplugged. but it makes no big difference. It decreases amount of memory leak but does not fix my problem.
private void CloseAndDisposeSerialPort()
{
var localRefToPort = DeviceSerialPort;
DeviceSerialPort = null;
try
{
if (localRefToPort == null) return;
try
{
localRefToPort.Close();
}
catch (Exception cex)
{
//do logging
}
finally
{
try
{
localRefToPort.Dispose();
}
catch (Exception dex)
{
//do logging
}
}
}
catch (Exception ex)
{
//do logging
}
}
Out of memory stacks I was able to get from UnhandledExceptionHandler.
Exception of type 'System.OutOfMemoryException' was thrown.
at System.IO.Ports.SerialStream.EventLoopRunner.WaitForCommEvent()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
Next stack I got when I was reading from port. (code example above does not have it)
Exception of type 'System.OutOfMemoryException' was thrown.
at Microsoft.Win32.Win32Native.CreateEvent(SECURITY_ATTRIBUTES lpSecurityAttributes, Boolean isManualReset, Boolean initialState, String name)
at System.Threading.EventWaitHandle..ctor(Boolean initialState, EventResetMode mode, String name)
at System.Threading.ManualResetEvent..ctor(Boolean initialState)
at System.IO.Ports.SerialStream.BeginReadCore(Byte[] array, Int32 offset, Int32 numBytes, AsyncCallback userCallback, Object stateObject)
at System.IO.Ports.SerialStream.ReadByte(Int32 timeout)
at System.IO.Ports.SerialStream.ReadByte()
at System.IO.Ports.SerialPort.ReadByte()
at TestClass.SerialPortDataReceived(Object sender, SerialDataReceivedEventArgs e)
There is an article on MSDN that I suppose related to my problem. But I am not sure how I can apply suggested resolution. It is almost two weeks that I am fighting with this problem. I tried to detect device disconnection moment and close/dispose port as soon as possible but it did not help. Any suggestion is much appreciated.
