Following some of the samples posted in Mike Stall’s blog and after actually needing something like this at work, I’ve decided to write a small program called ExceptionDbg which uses MDbg’s APIs and tracks all exceptions being thrown in an application (including those that are being swallowed by try..catch blocks).

We had a case of exceptions being thrown in the finalization code (this is C++ code that has destructors and therefore has finalizers. I’ve talked about C++ destructor in this previous post).

ExceptionDbg let you attach to a process and dump all of the exceptions being thrown live to your console and/or log file.

There are a few filters on the exception types being logged including:

  • Show only exceptions being caught by try..catch blocks
  • Show full Call Stack and if debug symbols are present, show line numbers as well as source file names.

So what is it good for, you ask?

  • Check exceptions in the finalizer thread – These exceptions are ALWAYS being caught so the finalizer thread will not die. It can mean that if you have some code that frees some unmanaged resources they will not get freed and this is a potential memory leak.
  • Got a performance problem? Check how what are all the exceptions being thrown and caught (try..catch blocks) to verify that some pieces of code doesn’t use exception throwing as a logic to handle things other than failure.

As you can see, it’s useful for a number of scenarios and it help me a lot in finding some of these problems.

You can get the binaries here and the source code here.

You need the .NET Framework 2.0 for this which can be downloaded from here.
If you want to compile it you’ll need the .NET Framework 2.0 SDK which you can download from here.

Enjoy and send me feedback!