[Insight-developers] PROPOSAL: Change default build type to "Release"

[Bill Lorensen]

There is a HUGE performance hit if ITK is built with Debug, especially on
Windows. It can be 10-30 times slower. I don't think that VTK has as much
degradation. I think it is because of the iterator loops that can be
flattened by a smart compiler, and the heavy use of templates.

I think the default should be Release. Developers should be smart enough to
build with Debug, but the typical user is not smart enough to change to
Release.


On Sat, Jul 23, 2011 at 12:35 PM, Marcus D. Hanwell <
marcus.hanwell at kitware.com> wrote:

> Hans,
>
> I never really understood what an empty build type meant, and on MSVC
> there is a default. For Titan, VTK, and others I added a default of
> Debug to the CMakeLists.txt.
>
> On Sat, Jul 23, 2011 at 12:28 PM, Johnson, Hans J
> <hans-johnson at uiowa.edu> wrote:
> > ITK developers,
> > One of the most common reasons for not using ITK is a perception that it
> is
> > really slow.  In my experience of working with newcomers to ITK, I find
> that
> > their first experience (and often their first year of experience) is with
> > the most default build of ITK possible.  It is very common that the first
> > impressions of ITK are based on whatever is produced by "mkdir –p
> ITK-build;
> > cmake ../ITK; make".
> > Mostly as a marketing tactic to improve initial impressions of ITK, I'd
> > suggest that the "mkdir –p ITK-build; cmake ../ITK; make" builds ITK in
> > "Release" mode.
>
> Have you considered using Debug as the default for the development
> tree, and switching that default to Release when making release
> tarballs? This is something I have done, and it seems to have been
> well received (or not noticed). So developers get a default they might
> expect, and users get one that they might expect.
>
> I would also suggest using -O2 with GCC for release rather than the
> default -O3 from CMake release, but that may well be a different
> discussion. Just my $0.02 from my experience working on various CMake
> based projects (largely from the Linux/Mac perspective).
>
> Marcus
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