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.<br><br>Great to hear talk of testing performance regressions on the dashboard -- looking forward to the day that's a reality.<div><br></div><div>Thx,</div><div>David C.</div><div><br></div><div><br>On Friday, December 12, 2014, David Gobbi <<a href="mailto:david.gobbi@gmail.com">david.gobbi@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">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.<div><br></div><div>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.</div><div><br></div><div> - David</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 12, 2014 at 5:12 PM, Berk Geveci <span dir="ltr"><<a href="javascript:_e(%7B%7D,'cvml','berk.geveci@kitware.com');" target="_blank">berk.geveci@kitware.com</a>></span> wrote:<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">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:<div><br></div><div>* Garbage collection</div><div>* vtkDataArrayTemplate::DataChanged()</div><div>* Abundant use of Modified()</div><div>* Progress reporting</div><div><div><br></div><div>Very nice and convenient feature. They may lead to a code running more slowly as more threads are added rather than scale up.</div><div><br></div><div>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).</div></div><div><br></div><div>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.</div><div><br></div><div>Best,</div><div>-berk</div><div><br></div><div><br></div><div><br></div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 12, 2014 at 9:52 AM, David Gobbi <span dir="ltr"><<a href="javascript:_e(%7B%7D,'cvml','david.gobbi@gmail.com');" target="_blank">david.gobbi@gmail.com</a>></span> wrote:<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>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.</div><span><font color="#888888"><div><br></div><div> - David</div></font></span><div><div><br><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 12, 2014 at 7:24 AM, Andras Lasso <span dir="ltr"><<a href="javascript:_e(%7B%7D,'cvml','lasso@queensu.ca');" target="_blank">lasso@queensu.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">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.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Adding the macro has negligible impact on VTK but would help application developers.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Andras<u></u><u></u></span></p>
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<p class="MsoNormal"><a name="14a419176b39b0e8_14a40fd7b2e60853_14a3efd3a80a3d69_14a3ee31cd8020f7__MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"><u></u> <u></u></span></a></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> David Gobbi [mailto:<a href="javascript:_e(%7B%7D,'cvml','david.gobbi@gmail.com');" target="_blank">david.gobbi@gmail.com</a>]
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<b>Sent:</b> Friday, December 12, 2014 09:16<br>
<b>To:</b> <a href="javascript:_e(%7B%7D,'cvml','vtk-developers@vtk.org');" target="_blank">vtk-developers@vtk.org</a><br>
<b>Cc:</b> Jean-Christophe Fillion-Robin; Berk Geveci; Andras Lasso<br>
<b>Subject:</b> Re: [vtk-developers] Proposal to add "vtkInfoMacro"<u></u><u></u></span></p><div><div>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal">Summary: this is a convenience feature, IMHO a mostly harmless one, and one that I might use.<u></u><u></u></p>
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<p class="MsoNormal"> - David<u></u><u></u></p>
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<p class="MsoNormal">On Fri, Dec 12, 2014 at 6:27 AM, Berk Geveci <<a href="javascript:_e(%7B%7D,'cvml','berk.geveci@kitware.com');" target="_blank">berk.geveci@kitware.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal">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).<u></u><u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal">Best,<u></u><u></u></p>
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<p class="MsoNormal">-berk<u></u><u></u></p>
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<p class="MsoNormal">On Thu, Dec 11, 2014 at 12:06 PM, Jean-Christophe Fillion-Robin <<a href="javascript:_e(%7B%7D,'cvml','jchris.fillionr@kitware.com');" target="_blank">jchris.fillionr@kitware.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hi Folks, <u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">While developing 3D Slicer, we created a macro named
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vtkInfoMacro<br>
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similar to "vtkErrorMacro/vtkDebugMacro/vtkWarningMacro".<br>
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<p class="MsoNormal">We would like to contribute it back to VTK core.<u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">The associated topic is: <br>
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<a href="http://review.source.kitware.com/#/c/18385/" target="_blank">
http://review.source.kitware.com/#/c/18385/</a><br>
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<p class="MsoNormal" style="margin-bottom:12.0pt">It would be great to get feedback before moving forward.<u></u><u></u></p>
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<p class="MsoNormal">Thanks<u></u><u></u></p>
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<p class="MsoNormal"><span style="color:#888888">Jc<u></u><u></u></span></p>
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