Testing threading

[Warren Postma]

George Sakkis wrote:
> How one goes on testing a threaded program, apart from doing a few
> successful runs and crossing his fingers that it at least follows the
> 'correct 99.9999% of the time' rule ? 

If you haven't been in there and stepped through all the code, looked 
for a reasonable set of test cases, and tried those test cases, then you 
haven't tested! :-)

You test a threaded program the same way you test a non-threaded
program. Thoroughly.  Test cases. YOu don't *have* to write unit tests,
but it sure helps. Code running a few times isn't tested.  If you
prefer to test manually, really want to be thorough you have to find 
ways to make sure you've done coverage of a reasonable set of test 
cases.  How do I get myself a set of test cases? Personally I like to 
walk through my code in a debugger and ask myself "how could this go 
wrong?".  "What if I pass a huge amount of data in here? How 
unresponsive can I find ways to make this thread get?" "If this is a 
network communications thread, let's try all the various error 
conditions that can happen on a real network.". ...

When I think of an idea on how things could go wrong ("What happens if
the data isn't here or is invalid?"/"Where should I be catching 
exceptions and how should I be handling them?")

Regards,

Warren