[Interest] Best way to terminate threads using QWaitCondition

[Bob Hood]

On 11/21/2015 2:26 PM, Bob Hood wrote:
> On 11/21/2015 1:26 PM, Thiago Macieira wrote:
>>> that are synchronizing using QMutex/QWaitCondition.  In my working
>>> code, I'm getting error messages that look like:
>>>
>>>       QWaitCondition: cv destroy failure: Device or resource busy
>>>       QWaitCondition: mutex destroy failure: Device or resource busy
>> What's the backtrace of those warnings? Which thread were they printed from?
>
> I'm getting them from the child process that has the threads.  The process 
> is being launched from a parent using QProcess.  I'm trapping the child's 
> stdout and stderr, and these are coming through on the stderr.
>
> I'll attach at debugger to the child and see if I can pinpoint the thread.

Well, my Debugging-fu under Linux is not quite as good yet as it is under 
Windows.  I cannot pin down the precise thread that might be causing this, or 
even the point in time.  However, my gut tells me that it's a race condition 
where the variables (QMutex/QWaitCondition) are being destroyed before the 
threads are terminated.

I'm going to try some refactoring of the threading model to see if I can 
address it that way.  This is my first use of wait conditions (although I've 
used a similar synchronization model in Python).  It's a great approach to 
thread synchronization, but it's turning out to be tricky.  :)

Thanks for the help, Thiago.  I'll get back to you if I can't address it some 
other way.