Very slow compile times on Visual Studio 2005

The Chromium.org team listed several options for accelerating the build (at this point about half-way down the page):

In decreasing order of speedup:

• Install Microsoft hotfix 935225.
• Install Microsoft hotfix 947315.
• Use a true multicore processor (ie. an Intel Core Duo 2; not a Pentium 4 HT).
• Use 3 parallel builds. In Visual Studio 2005, you will find the option in Tools > Options... > Projects and Solutions > Build and Run > maximum number of parallel project builds.
• Disable your anti-virus software for .ilk, .pdb, .cc, .h files and only check for viruses on modify. Disable scanning the directory where your sources reside. Don't do anything stupid.
• Store and build the Chromium code on a second hard drive. It won't really speed up the build but at least your computer will stay responsive when you do gclient sync or a build.
• Defragment your hard drive regularly.
• Disable virtual memory.

I had a similar issue on a solution with 21 projects and 1/2 million LOC. The biggest difference was getting faster hard drives. From the performance monitor the 'Avg. Disk Queue' would jump up significantly on the laptop indicating the hard drive was the bottle neck.

Here's some data for total rebuild times...

1) Laptop, Core 2 Duo 2GHz, 5400 RPM Drive (not sure of cache. Was standard Dell inspiron).

Rebuild Time = 112 seconds.

2) Desktop (standard issue), Core 2 Duo 2.3Ghz, single 7200RPM Drive 8MB Cache.

Rebuild Time = 72 seconds.

3) Desktop Core 2 Duo 3Ghz, single 10000 RPM WD Raptor

Rebuild Time = 39 seconds.

The 10,000 RPM drive can not be understated. Builds where significantly quicker plus everything else like displaying documentation, using file explorer was noticable quicker. It was a big productivity boost by speeding the code-build-run cycle.

Given what companies spend on developer salaries it is insane how much they can waste buy equiping them with the same PCs as the receptionist uses.

Turn off your antivirus. It adds ages to the compile time.

Use distributed compilation. Xoreax IncrediBuild can cut compilation time down to few minutes.

I've used it on a huge C\C++ solution which usually takes 5-6 hours to compile. IncrediBuild helped to reduce this time to 15 minutes.

If this is C or C++, and you're not using precompiled headers, you should be.

We had a 80+ projects in our main solution which took around 4 to 6 minutes to build depending on what kind of machine a developer was working. We considered that to be way too long: for every single test it really eats away your FTEs.

So how to get faster build times? As you seem to already know it is the number of projects that really hurt the buildtime. Of course we did not want to get rid of all our projects and simply throw all sourcefiles into one. But we had some projects that we could combine nevertheless: As every "Repository project" in the solution had its own unittest project, we simply combined all the unittest projects into one global-unittest project. That cut down the number of projects with about 12 projects and somehow saved 40% of the time to build the entire solution.

We are thinking about another solution though.

Have you also tried to setup a new (second) solution with a new project? This second solution should simply incorporates all files using solution folders. Because you might be surprised to see the build time of that new solution-with-just-one-project.

However, working with two different solutions will take some carefull consideration. Developers might be inclined to actually -work- in the second solution and completely neglect the first. As the first solution with the 70+ projects will be the solution that takes care of your object-hierarchy, this should be the solution where your buildserver should run all your unittests. So the server for Continous Integration must be the first project/solution. You have to maintain your object-hierarchy, right.

The second solution with just one project (which will build mucho faster) will than be the project where testing and debugging will be done by all developers. You have to take care of them looking at the buildserver though! If anything breaks it MUST be fixed.

Make sure your references are Project references, and not directly to the DLLs in the library output directories.

Also, have these set to not copy locally except where absolutely necessary (The master EXE project).

I posted this response originally here: https://stackoverflow.com/questions/8440/visual-studio-optimizations#8473 You can find many other helpful hints on that page.

If you are using Visual Studio 2008, you can compile using the /MP flag to build a single project in parallel. I have read that this is also an undocumented feature in Visual Studio 2005, but have never tried myself.

You can build multiple projects in parallel by using the /M flag, but this is usually already set to the number of available cores on the machine, though this only applies to VC++ I believe.

How big is your build directory after doing a complete build? If you stick with the default setup then every assembly that you build will copy all of the DLLs of its dependencies and its dependencies' dependencies etc. to its bin directory. In my previous job when working with a solution of ~40 projects my colleagues discovered that by far the most expensive part of the build process was copying these assemblies over and over, and that one build could generate gigabytes of copies of the same DLLs over and over again.

Here's some useful advice from Patrick Smacchia, author of NDepend, about what he believes should and shouldn't be separate assemblies:

http://codebetter.com/patricksmacchia/2008/12/08/advices-on-partitioning-code-through-net-assemblies/

There are basically two ways you can work around this, and both have drawbacks. One is to reduce the number of assemblies, which is obviously a lot of work. Another is to restructure your build directories so that all your bin folders are consolidated and projects do not copy their dependencies' DLLs - they don't need to because they are all in the same directory already. This dramatically reduces the number of files created and copied during a build, but it can be difficult to set up and can leave you with some difficulty pulling out only the DLLs required by a specific executable for packaging.

Perhaps take some common functions and make some libraries, that way the same sources are not being compiled over and over again for multiple projects.

If you are worried about different versions of DLLs getting mixed up, use static libraries.

Turn off VSS integration. You may not have a choice in using it, but DLLs get "accidentally" renamed all the time...

And definitely check your pre-compiled header settings. Bruce Dawson's guide is a bit old, but still very good - check it out: http://www.cygnus-software.com/papers/precompiledheaders.html

I have a project which has 120 or more exes, libs and dlls and takes a considerable time to build. I use a tree of batch files that call make files from one master batch file. I have had problems with odd things from incremental (or was it temperamental) headers in the past so I avoid them now. I do a full build infrequently, and usually leave it to the end of the day while I go for a walk for an hour (so I can only guess it takes about half an hour). So I understand why that is unworkable for working and testing.

For working and testing I have another set of batch files for each app (or module or library) which also have all the debugging settings in place -- but these still call the same make files. I may switch DEBUG on of off from time to time and also decide on builds or makes or if I want to also build libs that the module may depend on, and so on.

The batch file also copies the completed result into the (or several) test folders. Depending of the settings this completes in several seconds to a minute (as opposed to say half an hour).

I used a different IDE (Zeus) as I like to have control over things like .rc files, and actually prefer to compile from the command line, even though I am using MS compliers.

Happy to post an example of this batch file if anyone is interested.

Disable file system indexing on your source directories (specifically the obj directories if you want your source searchable)

If this is a web app, setting batch build to true can help depending on the scenario.

<compilation defaultLanguage="c#" debug="true" batch="true" >  

You can find an overview here: http://weblogs.asp.net/bradleyb/archive/2005/12/06/432441.aspx

One cheaper alternative to Xoreax IB is the use of what I call uber-file builds. It's basically a .cpp file that has

#include "file1.cpp"
#include "file2.cpp"
....
#include "fileN.cpp"

Then you compile the uber units instead of the individual modules. We've seen compile times from from 10-15 minutes down to 1-2 minutes. You might have to experiemnt with how many #includes per uber file make sense. Depends on the projects. etc. Maybe you include 10 files, maybe 20.

You pay a cost so beware:

1. You can't right click a file and say "compile..." as you have to exclude the individual cpp files from the build and include only the uber cpp files
2. You have to be careful of static global variable conflicts.
3. When you add new modules, you have to keep the uber files up to date

It's kind of a pain, but for a project that is largely static in terms of new modules, the intial pain might be worth it. I've seen this method beat IB in some cases.

You also may want to check for circular project references. It was an issue for me once.

That is:

Project A references Project B

Project B references Project C

Project C references Project A

Nice suggestions that have helped so far (not saying there aren't other nice suggestions below, if you are having issues, I recommend reading then, just what has helped us)

• New 3GHz laptop - the power of lost utilization works wonders when whinging to management
• Disable Anti Virus during compile
• 'Disconnecting' from VSS (actually the network) during compile - I may get us to remove VS-VSS integration altogether and stick to using the VSS UI

Still not rip-snorting through a compile, but every bit helps.

We are also testing the practice of building new areas of the application in new solutions, importing in the latest dlls as required, them integrating them into the larger solution when we are happy with them.

We may also do them same to existing code by creating temporary solutions that just encapsulate the areas we need to work on, and throwing them away after reintegrating the code. We need to weigh up the time it will take to reintegrate this code against the time we gain by not having Rip Van Winkle like experiences with rapid recompiling during development.

Orion did mention in a comment that generics may have a play also. From my tests there does appear to be a minimal performance hit, but not high enough to sure - compile times can be inconsistent due to disc activity. Due to time limitations, my tests didn't include as many Generics, or as much code, as would appear in live system, so that may accumulate. I wouldn't avoid using generics where they are supposed to be used, just for compile time performance

It's sure there's a problem with VS2008. Because the only thing I've done it's to install VS2008 for upgrading my project which has been created with VS2005. I've only got 2 projects in my solution. It isn't big. Compilation with VS2005 : 30 secondes Compilation with VS2008 : 5 minutes