NullReferenceException，没有堆栈跟踪...从哪里开始？ [英] NullReferenceException, no stack trace... where to start?

问题描述

我有一个WPF音频应用程序。

I have a WPF audio application.

偶尔（甚至在调试器中）我看到一个 NullReferenceException 它不带有堆栈跟踪信息。

Occasionally (and even in the debugger) I'm seeing a NullReferenceException which carries no stack trace information with it.

如何开始调试这样的问题？

How can one start debugging such an issue?

一些背景：

我是P $调用 WinMM.dll 中的函数，涉及注册回拨，当调用 waveOutOpen

I'm P/Invoking functions in WinMM.dll which involves registering a callback when calling waveOutOpen

    [DllImport("winmm.dll")]
    public static extern MmResult waveOutOpen(out IntPtr phwo, IntPtr uDeviceID, WaveFmt pwfx, WaveCallbk dwCallback, IntPtr dwInstance, int fdwOpen);

这证明难以稳定，特别是在我调用 waveOutClose ，并立即调用 waveOutOpen （通常更改输出格式）。

This has proved difficult to get stable, especially at the point where I call waveOutClose, and immediately call waveOutOpen again (usually to change the output format).

我怀疑这个问题可能与上面描述的电话有关（尽管知之甚少，我可以完全失去目标）。

I suspect that the problem may be related to the calls I've been describing above (although on so little knowlege, I could be completely off-target).

复制目前的问题是难以捉摸的，虽然我可以为一个相当一贯地看到这个问题的用户提供一个构建。我可能会尝试加速导致问题的操作，以便在调试器中再现问题更加确定。

Reproducing the problem is currently proving elusive, although I can supply a build to a user who is fairly consistently seeing this problem. I might try to speed up the operations that are causing the problem to the point where reproducing the problem in the debugger is more of a certainty.

关于调试器，我没有修改任何设置（包括启用非托管代码调试）或任何 Debug - >例外... 设置。说实话，我对这里提供的东西很无聊，所以欢迎任何提示。

With regards to the debugger, I haven't tinkered with any of the settings (including Enable unmanaged code debugging) or any of the Debug -> Exceptions... settings. To be honest, I'm fairly clueless about what's on offer here, so any hints are welcome.

异常怎么可能没有堆栈跟踪？你以前见过吗？帮助！

How might an exception not have a stack trace? Have you seen this before? Help!

推荐答案

在调试器中可以做的最有用的工作是指示它打破第一次机会异常（Debug - >异常）：

The most helpful thing you can do in the debugger is instruct it to break on a first-chance exception (Debug -> Exceptions):

这将导致调试器的一个中断，确切地说，一个 NullReferenceException 被抛出，这几乎是最好的您可以希望在调试时。

This will cause a break into the debugger at the exact point a NullReferenceException is thrown, which is pretty much the best you can ever hope for while debugging.

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