Question

We have an application made up by a host (exe) and a lot of modules (dlls) containing gui etc.
Sometimes, the application freezes on shutdown. Mostly it happens during testing through TestComplete. We are not able to reproduce the behavior during debugging.

How can we find out why the application freezes?

I would guess that it is related to threads, but I do not know for sure.

Are there any tools or techniques we should try out?

Answer 1

I think that good old logging would help you. Add some logging to every unit finalization, add such logging to destructors of global data (database connection, global configuration etc). Of course do not destroy logger object.

If your application is multithreaded then add some logging to working threads such as writing ‘[date] thread [name of class] working’ and write it every few seconds (you can use some debug mode). Also add logging when thread discovers that it should terminate.

Also use some system utilites such as ProcessMonitor, Handles, Process Explorer (all by Sysinternals/Microsoft). Monitor disk reads/writes, handle count, memory usage, network connections. Maybe your application dumps some big structures on disk at exit? Maybe it allocated a lot of memory and must release it?