在应用程序运行时随时启动Visual Studio调试器

Question

I am developing an application using Visual Studio, and when I install it (via Setup Project, .msi file) in a client machine and run it, I get some "Heisenbug" exception. I am almost sure the error comes from earlier in the codepath, so I would like to debug it.

Fact is: when the application crashes, the following dialog is displayed (referring to my application instead of Windows Explorer, of course):

and if I choose "Debug the program", the Visual Studio Debugger (which is somehow available in the deployed machine) starts and shows details from the exception.

What I would like to do is to start the debugging session from the very start , so I can go on hitting F10 and F11 and check some intermediate values.

Anyone know how can I start the Visual Studio debugging session at any time while the application is running? Not that I am running the deployed application, not starting it from Visual Studio.

Answer 1

Since you have Visual Studio up and running on the machine running the deployed application, it should be straightforward:

1. Run the application
2. Load the project in Visual Studio
3. Go to DEBUG -> Attach to process...

4. A list will pop up with all the running processes

   From the list, pick the process corresponding to the application, it should be named after your exe (if you sort by the numeric IDs, it's very likely it will be near the highest end)

5. Click "Attach", Visual Studio will should start debugging similarly as when you normally start with F5 .

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I also have another suggestion: implement heavy logging until you have everything figured out. Write down everything you have doubts about for further analysis in case something goes wrong: values, queries, etc.

Answer 2

You can start the application directly under the Visual Studio Debugger using the debugexe parameter :

devenv /debugexe “C:\\MyApplication\\Debug\\MyApplication.exe”

This will launch the application with the debugger immediately attached. Otherwise it's very hard to debug issues that happen at the time the application is starting. You won't be able to manually attach in time to catch any events that happen during this time.

You can also place the following piece of code at the first line of you application (usually the Main(string[] args)) to force a debugger to attach and cause the application to break immediately :

System.Diagnostics.Debugger.Break();

If your application starts and runs fine for some time, you can use the "Attach to Program" feature as described by @Alex.

If you don't have the sources available on the target machine, you can either copy them over, or if you're using Source and Symbol Indexing features of TFS Team Build, you can tell the debugger where to look for your Debug Symbols (which will then resolve to TFS source control automatically).