[mmarks]

Not to take away from your point, but in my experience the vast majority of C++ build pipelines even at major companies can still be improved. Few people enjoy 'improving the build', it often touches everything, and requires discipline to keep it working. Most of the projects I've worked on have been larger than Chrome, I've seen the compile time for BioShock Infinite go from 2 hours down to 15 minutes with serious work on header use, precompiled headers, and all the other tricks people use. Epic's build system is a pretty good example. There is even a older book, Large-scale C++ Design, that is specifically about this point.

Starting with a full build that initially takes hours and it shrinking to < 15-20 minutes and better seems pretty par for the course for truely large C++ projects. You don't get a fast build process for free, but if the team makes it a priority, alot can be done.

EDIT: Times mentioned were for a full build, often you rarely due a full build, incremental builds should be majority. Places that don't make incremental builds 100% reliable drive me crazy and waste so much developer time. This is common, but it's a lame excuse. Just do the work and fix it.

[evmar]

I worked on exactly this problem for Chrome! I agree with all your major points -- in particular, optimizing incremental builds is the most important thing for developer sanity.

Here's a post about what I did: http://neugierig.org/software/chromium/notes/2011/02/ninja.h...

[mmarks]

Doom 3 actually used Scons across all the OSes (~2004). At the time, it was so nice to have a python build system. I sort of hoped it was the future, but it sort of died as it failed to scale. I've seen a few home-brewed python build systems work well, but typically we're back to CMake/Make

[gue5t]

Check out meson; it seems to be the future for projects that were using CMake or autotools. It's certainly a joy to work with in comparison.

[xorcist]

Were using? I quite enjoy CMake and find it fast and easy to use. What am I missing out on?

[gue5t]

Meson is strongly-typed; it goes beyond just having a notion of "paths" and tracks what kind of object paths point to, and what kind of resource strings name. This is invaluable, because it means you get feedback when you accidentally pass an object file instead of a library name or any number of other confusions.

Personally, this meant the error messages I got were helpful enough that my first meson-built project was working after a half-hour of deciding to port it over despite using several system libraries and doing compile-time code generation.

Meson's language is not Turing-complete, so it's easy to analyze for errors. Unlike CMake and autotools, Meson's language looks like a real (pythonish) programming language, and it isn't string-oriented; dances of escaping, substitution, and unescaping are uncommon.

Compared to autotools or hand-rolled Makefiles, CMake is a step in the right direction; meson is a leap.

[adrianratnapala]

How happy have you been with Meson in complicated projects with multiple directories. Especially where things are complex and different options are used in different places. Make, in spite of all it's craziness would be a good tool if it any sane kind of support for this.

CMake tries hard to to do better, but then introduces its own layers of craziness. So it's fine as long as I am not doing anything unusual, but as soon as I need to understand what is going on, I find a dizzying array of barely working moving parts beneath me.

[inglor]

Just as a data point - Chrome has more code than the linux kernel - Would you say BioShock Infinite seriously has a larger code base than Chrome?

I think a lot of people don't estimate correctly just how huge Chrome is.

[mmarks]

I would expect kernels to be quite small (#file, line-count) compared to major Applications like Unreal Games and Civilization 5. I've never worked on Chrome, but I can safely say the amount of source code in a few Unreal Games and Civilization5 dwarfs the drivers and OS code I've worked on. Take Unreal then add a team of developers adding onto it for multiple years thru multiple releases. Then add all the middleware (Havok, AudioEngines, NaturalMotion).

OS are much larger than kernel, I'd guess all the driver code exceeds the actual kernel.

People always think they code base is large, but having built most of the Call of Duties and many Unreal games, all the OS code I've worked on is trivial in size comparison. There is probably something bigger, but games seem bigger than many major apps in my experience.

[joshuamorton]

For reference, the kernel has ~15 million LoC, and according to a not exactly reliable or verifiable infographic on reddit, BioShock infinite contains 631 miles, which would be between 3 and 10 million LoC.

[mirekrusin]

Also, Linux kernel is C vs the mentioned rest C++.

[vborovikov]

Why is it so big?

[SolarNet]

It's an operating system (pretending to be a browser).

[marcosdumay]

It is also an interpreter for a big number of convoluted (and a bigger still of non-convoluted) languages.

[brucedawson]

A lot of time has been spent on optimizing Chrome's build: - Ninja build system will perfectly parallelize the build without overloading resources (modulo this OS bug) - Meta-build system was recently completely replaced (gyp-> gn) to improve builds - Lots of work on clang-cl to allow compiling Chrome for Windows without using Microsoft's compiler - Distributed build system to further increase parallelism

So, lots of work has been done to deal with the build times. And probably not a lot of low hanging fruit to be found. But, still more work is being done. Support is being added for 'jumbo' builds (aka unity builds, where multiple translation units are #included into one) which is helping a bit with compile and link times.

[mmarks]

Unity builds are a big win in Unreal Engine and basically required w/Unreal, the actual win is surprising large.

EDIT: I'm sure lots of work has been done, not trying to degrade that. Just sharing my experience on my projects, never worked with Chrome.