[vtk-developers] Proposal to add "vtkInfoMacro"

Sat Dec 13 14:54:49 EST 2014

Thanks for the pointer, Bill. The logger in ITK is quite nice and the info level logging macro is available in ITK: if the output window is set to itkLoggerOutput then

itkGenericOutputMacro

calls

this->m_Logger->Write(LoggerBase::INFO, t)

I don't think that adding an ITK-like logger to VTK is necessary, just adding the missing vtkInfo (or vtkGenericOutput) macro would be enough.

Andras

-----Original Message-----
From: Bill Lorensen [mailto:bill.lorensen at gmail.com] 
Sent: Saturday, December 13, 2014 13:47
To: Andras Lasso
Cc: David Cole; David Gobbi; vtk-developers at vtk.org; Berk Geveci
Subject: Re: [vtk-developers] Proposal to add "vtkInfoMacro"

ITK has a logger, itk::Logger.

On Sat, Dec 13, 2014 at 11:35 AM, Andras Lasso <lasso at queensu.ca> wrote:
> Yes, sure we don’t need VTK to include a complete logging framework 
> such as log4cpp. We just need a convenient mechanism to send messages 
> to logging frameworks from VTK.
>
>
>
> What do you think about the following?
>
>
>
> * Allow completely disable vtkInfoMacro by an #ifdef (for example, if 
> #ifndef VTK_INFO_ENABLED then vtkInfoMacro is an empty statement; we 
> can set VTK_INFO_ENABLED to false by default)
>
>
>
> * Put the macro in a separate header in Common/vtkInfo.h to not make 
> the macro visible to VTK classes by default. GUISupport directory 
> would be too restrictive, as logging is not related to GUI and there 
> are other application-only functions in Common already (such as 
> vtkOutputWindow::DisplayText), but any other suggestion is welcome.
>
>
>
> Andras
>
>
>
> From: David Cole [mailto:DLRdave at aol.com]
> Sent: Saturday, December 13, 2014 09:28
> To: David Gobbi
> Cc: Berk Geveci; vtk-developers at vtk.org; Andras Lasso
>
>
> Subject: Re: [vtk-developers] Proposal to add "vtkInfoMacro"
>
>
>
> I agree with Berk. VTK should NOT include the kitchen sink... This 
> belongs elsewhere -- there are whole separate libraries that are 
> actually focused on logging, and doing it in a high performance, high functionality manner.
> log4cpp, g2log, and boost all come to mind.
>
> Great to hear talk of testing performance regressions on the dashboard 
> -- looking forward to the day that's a reality.
>
>
>
> Thx,
>
> David C.
>
>
>
>
> On Friday, December 12, 2014, David Gobbi <david.gobbi at gmail.com> wrote:
>
> Well, vtkImageReslice is probably not the best "speed" example any 
> more, it has become fat with all the features that I've added to it 
> over the years :) And in the old days, a big reason for its speed was 
> that it did some bit-twiddling to work around the disastrously slow 
> floor() operations on old CPUs.
>
>
>
> However, it is certainly true with modern computer architectures, with 
> their multiple cores and fast caches, doing _any_ application-level or 
> system-level operations within the algorithmic code causes a 
> significant performance hit, because that takes the CPU core out of 
> the "zone" where it can work at its full potential.
>
>
>
>  - David
>
>
>
> On Fri, Dec 12, 2014 at 5:12 PM, Berk Geveci <berk.geveci at kitware.com>
> wrote:
>
> I'd be fine with it if the header is put into a higher level module 
> such as GUISupport and has some examples demonstrating its purpose and 
> some documentation providing a guide on how to use it. I would not 
> agree to putting this at a place where it may encourage folks to use 
> it in algorithms and other core functionality. As I mentioned 
> previously, I already have the unpleasant job of ripping out a number 
> of "convenience" functionality that are going to have significant 
> impact on performance as we continue to multi-thread more algorithms. 
> All of these features look harmless when initially added. Then they 
> find their way into core functionality slowly but surely. When you are 
> considering 200-way parallelism (which we are, since we are porting to Intel Xeon Phi already), any little bit makes a difference.
> Some simple examples:
>
>
>
> * Garbage collection
>
> * vtkDataArrayTemplate::DataChanged()
>
> * Abundant use of Modified()
>
> * Progress reporting
>
>
>
> Very nice and convenient feature. They may lead to a code running more 
> slowly as more threads are added rather than scale up.
>
>
>
> I don't agree that misuse of such features would get caught in 
> reviews. Very few reviewers are conscious of potential performance 
> issues. Because very few developers are performance conscious at this 
> point (Dave Gobbi excepted, he writes amazingly fast code, see image reslice).
>
>
>
> So this is not the time to pepper core classes with convenience 
> functionality. It is time to simplify and come with very clear 
> guidelines on what core classes and algorithms can and cannot do. Once 
> the development community becomes more aware of these issues and our 
> dashboards are able to catch performance regressions, we can relax some.
>
>
>
> Best,
>
> -berk
>
>
>
>
>
>
>
>
>
> On Fri, Dec 12, 2014 at 9:52 AM, David Gobbi <david.gobbi at gmail.com> wrote:
>
> However, I have reservations about putting this macro in vtkSetGet.h. 
> If it goes in its own header, then the chances of it being confused 
> with vtkDebugMacro are significantly reduced.
>
>
>
>  - David
>
>
>
>
>
> On Fri, Dec 12, 2014 at 7:24 AM, Andras Lasso <lasso at queensu.ca> wrote:
>
> I completely agree with David. This is an application support feature. 
> There are several examples for such features in VTK, including 
> QVTKWidget or vtkOutputWindow::DisplayText(). These are not meant to 
> be used in VTK library itself (other than examples and tests) but in 
> VTK-based applications. They make the life of application developers 
> easier, allow standardization, reduces code/feature duplication.
>
>
>
> Adding the macro has negligible impact on VTK but would help 
> application developers.
>
>
>
> Andras
>
>
>
>
>
> From: David Gobbi [mailto:david.gobbi at gmail.com]
> Sent: Friday, December 12, 2014 09:16
> To: vtk-developers at vtk.org
> Cc: Jean-Christophe Fillion-Robin; Berk Geveci; Andras Lasso
> Subject: Re: [vtk-developers] Proposal to add "vtkInfoMacro"
>
>
>
> On the one hand, I can see that it is useful to have a message macro 
> that doesn't require a debug build.  In my own apps, I often write 
> app-specific classes that are derived from vtkObject and this is a 
> macro that I might use from time to time.  Unlike Berk, I'm not all 
> that worried that it might be abused.  For VTK, we have code review.
>
>
>
> On the other hand, I don't think we have a use case for this within 
> VTK itself, it would be there purely to serve external VTK classes and apps.
> And people who need this feature could simply put this macro (or a 
> similar
> one) in their own header files.
>
>
>
> Summary: this is a convenience feature, IMHO a mostly harmless one, 
> and one that I might use.
>
>
>
>  - David
>
>
>
>
>
> On Fri, Dec 12, 2014 at 6:27 AM, Berk Geveci <berk.geveci at kitware.com>
> wrote:
>
> I disagree with this change. There is no compelling VTK specific 
> example for why this is needed. The examples are all from Slicer - 
> which to me says that they can be implemented in Slicer.
>
>
>
> Adding a logging functionality without clear guidelines on how to use 
> it is dangerous. It can lead to folks using it for debugging in 
> performance critical sections and since it is not compiled out in 
> Release builds, it can lead to significant performance issues, 
> specially in multi-threaded code. As it is, there are lot of minor 
> issues like this that we will have to go and clean up (progress being one of them).
>
>
>
> The main use case seems to be tracking interaction/workflow changes. 
> My suggestion is to employ a method appropriate to that. For example, 
> events and listeners.
>
>
>
> Best,
>
> -berk
>
>
>
>
>
> On Thu, Dec 11, 2014 at 12:06 PM, Jean-Christophe Fillion-Robin 
> <jchris.fillionr at kitware.com> wrote:
>
> Hi Folks,
>
> While developing 3D Slicer, we created a macro named
>
>                                           vtkInfoMacro
>
> similar to "vtkErrorMacro/vtkDebugMacro/vtkWarningMacro".
>
> We would like to contribute it back to VTK core.
>
>
>
> The associated topic is:
>
>                       http://review.source.kitware.com/#/c/18385/
>
> It would be great to get feedback before moving forward.
>
> Thanks
>
> Jc
>
>
>
>
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