How to debug why application dies exception-less, when another application is closed?

Question

I'm fixing bugs on an application, that is kind of data consumer/worker, getting data from third party application, using supplied API and libraries for doing so. It's c++ based API and the .net application is using a bit of c++ to access the libraries. Also - the application is multi-threaded, it's windowed (Winforms), uses several third party libraries (nhibernate, mysql and others). It might be relevant to add, that our consumer thread is the only place in the code, when it accesses the c++ library.

The problem? When the producent application is closing (takes a bit more time, more than a minute), consumer application dies within seconds, without error/exception - even thought they're opened independently. No information in Event Log, no Dr. Watson action, no exceptions in Visual Studio (debug just stops).

I've tried:

• Stepping throughout the code to see the moment, where it closes, but it always happened in different places, was it calling the producent's libraries code, or not.
• Debugged the application with Visual Studio configured to break on any exception throwing - but it dies without a thing.
• Creating crash dumps (using ADPlus.vbs) and using windbg on them (I'm new to such low-level debugging, though), but !analyze resulted with different stack traces - leaving me traceless.

What would be the good direction to find out why the consumer application dies? Is there a way, to get around the problem (like showing a prompt message to the user, like: "Producent application is closing, consumer application will do the same!")?

[EDIT]

Consumer application is multi-threaded, and it's one consumer thread as addon to UI thread. Also - the third party app we're using as producer uses COM to send information to any consumer app (aka add-on).

Me and my coworker decided to comment out some code, to find the code, that possibly makes the problem. And probably we've found it - the application dies if and only if we've registered our consumer to producer. After reading documentation for the third party app, it turned out that consumer apps have to actively query for message of closing the producer, otherwise they would be forcefully terminated by the producer app.

So: 95% that the problem is third party application which we're querying for data is sending COM message to forcefully terminate our application (I'll post info / change to wiki, if we'd test it's the only reason).

Answer 1

The general scenario described here is a source for a very common confusion and misunderstanding related to cases where one tries to understand 'how come my application vanished into thin air without leaving any trace?'.

The immediate assumtion would be: my application 'died' or 'crashed' or 'encountered such unexpected exception, which is even not visible to the debugger and thus did not create any dump-file. Happened to me few good times...

The real answer in most cases would be that the application did not realy crash or die and did not receive any excpetion, but was simply shutted-down gracefully, but from a flow that I did not expect.

The easiest way to debug such cases will be to put a breakpoint in kernel32!ExitProcess and to follow the stack and see how we got here.

Hope this helps