有未处理的异常时如何确保记录异常

Question

I want a crash reporting, so I register the UnhandledException event in App.xaml.cs like following. But there are 2 problems:

1. Sometimes, there is no callstacks for exception
2. Sometimes, I don't have enough time to write log into file before the process is terminated.

Any advice?

this.UnhandledException += App_UnhandledException;

private async void App_UnhandledException(object sender, UnhandledExceptionEventArgs e)
{
    if (!hasHandledUnhandledException)
    {
        e.Handled = true;
        _logger.Error("Unhandle exception - message = {0}\n StackTrace = {1}", e.Exception.Message, e.Exception.StackTrace);
        await CrashHandler.ReportExceptionAsync(e.Exception.Message, e.Exception.StackTrace);
        hasHandledUnhandledException = true;
        throw e.Exception;
    }
}

Answer 1

Make sure to access e.Exception only once. In some cases, information about the stacktrace is lost the second time you access the property . Save the exception in a variable and work directly with that variable. Also, as mentioned by Panagiotis Kanavos in the comments, directly log e.Exception.ToString() to make sure to miss no information. This will include the message, the callstack, and all inner exceptions (which you are not logging in your current code).

private async void App_UnhandledException(object sender, UnhandledExceptionEventArgs e)
{
    if (!hasHandledUnhandledException)
    {
        e.Handled = true;
        var exception = e.Exception;
        _logger.Error("Unhandled exception - {0}", exception);
        await CrashHandler.ReportExceptionAsync(exception.Message, exception.StackTrace);
        hasHandledUnhandledException = true;
        throw e.Exception;
    }
}

As for the problem of not having enough time to log the exception, it's controlled by the runtime so you can't do anything about it.