How to debug a hang process

http://blogs.msdn.com/b/kirillosenkov/archive/2008/12/07/how-to-debug-crashes-and-hangs.aspx


How to debug crashes and hangs



At my job on the C# IDE QA team I've learned some useful things about debugging in Visual Studio, which I'd like to summarize in this post. Although the screenshots were made using Visual Studio 2008 SP1, this pretty much applies to other versions of VS as well.



Rich debugging support



When you develop your C# application and hit F5, the target process (your program) gets started, and then the Visual Studio process attaches the debugger to the process where your code is running. This way, you can break into the debugger and VS will provide you with all sorts of rich debugging support - current statement highlighting, call stack, watches, locals, immediate window, Edit-and-Continue and so on.



More importantly, if your application throws an exception or crashes, the debugger will intercept that and provide your with all the information about the exception.



As a side note, in Visual Studio there is a way to run your code without attaching the debugger - the shortcut is Ctrl+F5. Try throwing an exception in your code when using F5 and Ctrl+F5 to feel the difference.



throw null;



By the way, my favorite way to artificially throw exceptions is throw null; I just love the fact that it throws a NullReferenceException because it can't find the exception object and nevertheless does exactly what I want it to do :)



Crashes and the Watson dialog



What if a program crashes or throws an exception, which you don't have source code for? Moreover, you didn't start the program using F5, but the operating system launched the process. I remember that before coming to Microsoft, the only thing I could do about some application crashing was to express my disappointment about the fact (usually in Russian). Now I don't feel helpless anymore, because I've learned a couple of tricks. As an example for this we'll crash Visual Studio itself and then debug the crash.



How to crash Visual Studio?



Viacheslav Ivanov reported an interesting crashing bug in our language service recently. Save all your work and then paste this code in a C# Console Application and change 'object' to 'int':



using System;



static class Program

{

static void Main()

{

ITest