[Insight-developers] threaded logger deadlock

[Bradley Lowekamp]

On May 3, 2011, at 1:23 PM, Kris Zygmunt wrote:

> Hello,
>     I am working on a multithreaded denoising filter for inclusion in  
> the Insight Journal and wanted to use either itkThreadLogger or  
> itkLoggerThreadWrapper to provide coherent multithreaded debug (at  
> least during development).  However, I have found that both of these  
> classes deadlock.  I noticed that the main test in Testing for each of  
> these classes does not actually test them in a multithreaded fashion  
> and have modified the tests accordingly.
> 
> I have a patch to fix the classes and update the tests, but I have a  
> few questions first.
> 
> 1.  Is there a way to have the itk test driver timeout if a test does  
> not finish (ie hangs or deadlocks) and log that as a failure?  If I  
> check the test code in against the current version of the classes, the  
> test will never end, which will likely mess up the rest of the test  
> process.

Perhaps this is what you are looking for:

http://www.cmake.org/cmake/help/cmake-2-8-docs.html#command:set_tests_properties

> 
> 2.  The main fix is to remove all references to m_WaitMutex, and only  
> use the main lock, m_Mutex to guard the queues.  As far as I can tell,  
> the purpose of the WaitMutex was to keep the logger thread from using  
> too much CPU to check for messages when the queues are empty.  I would  
> like to address this by adding a sleep for 0.5 or even 1 second  
> between checks if the queue is empty.  Will this approach work on all  
> targeted systems, Windows, Mac and Linux?  Solaris?  Is there another  
> approach that is recommended?
> 
> 3.  Should I create the patch just for ITK4 or for both ITK 3.20 and  
> ITK4?
> 
> 4.  Do I need to add a bug to the Mantis tracker first?
> 
> 5.  Should I remove all references to the threaded logger from my  
> multithreaded filter before inclusion in the Insight Journal, or wrap  
> it in some sort of compile option or something?  It is only useful to  
> log messages to the logger if the main application has actually  
> created an instance of the logger and given it to the filter.
> 
> Thanks!
> Kris
> 
> Kris Zygmunt
> SCI Institute
> University of Utah
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========================================================
Bradley Lowekamp  
Lockheed Martin Contractor for
Office of High Performance Computing and Communications
National Library of Medicine 
blowekamp at mail.nih.gov


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