调试：C# WinForms调用外部C++ DLL随机崩溃问题

背景 #

基于.NET Framework 4.6.1开发的WinForms应用，需持续调用C++编写的portavo.dll执行PH传感器读取逻辑，并根据实时PH值执行后续操作。应用整体运行看似正常，但会随机出现PH计通信中断，甚至直接崩溃，控制台输出两类错误信息：

错误信息1 #

Exception raised: System.FormatException in mscorlib.dll
Exception raised: System.FormatException in mscorlib.dll
The subprocess 0x3464 exited with code 0 (0x0)
Exception raised: System.Threading.ThreadAbortException in mscorlib.dll
The subprocess 0x3104 exited with code 0 (0x0)
The subprocess 0x363c exited with code 0 (0x0)
The application [...] exited with code 3221226356

错误信息2 #

Exception raised: System.Threading.ThreadAbortException in mscorlib.dll
The subprocess 0x3004 exited with code 0 (0x0)
The subprocess 0x323c exited with code 0 (0x0)
Exception raised: System.Threading.ThreadAbortException in mscorlib.dll
The subprocess 0x3562 exited with code 0 (0x0)
The subprocess 0x363c exited with code 0 (0x0)
Exception raised: System.Threading.ThreadAbortException in mscorlib.dll
The subprocess 0x395d exited with code 0 (0x0)
The subprocess 0x391e exited with code 0 (0x0)
The application [...] exited with code 3221225485

每次崩溃的错误码不同。崩溃前抛出的异常偶尔出现时应用仍能正常运行，但几乎可以确定崩溃是外部C++ DLL抛出的异常或错误导致的。

DLL调用代码示例 #

DllImport调用方式如下（其他方法采用相同模式）：

[DllImport("portavo.dll", EntryPoint = "PortavoInitDll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
private static extern void PortavoInitDll();
[DllImport("portavo.dll", EntryPoint = "PortavoSetTimingParam", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
private static extern void PortavoSetTimingParam(ushort to, byte trial);

public static unsafe void Init()
{
    PortavoInitDll();
    PortavoSetTimingParam(500, 2);
}

疑问 #

由于错误具有随机性（可正常运行4天或20小时后突然崩溃），无法有效调试定位问题，因此有以下疑问：

• 如何排查问题原因？
• 调用外部DLL的方式是否正确？据了解这是常规调用方式。
• 如何将外部DLL的函数调用放在独立线程中，避免其崩溃影响主程序？

猜测是DLL自身崩溃导致读取函数无法正常工作，进而引发程序崩溃。若能检测到崩溃，可通过Init函数重启DLL使程序恢复运行。

内容的提问来源于stack exchange，提问作者juan carlos