CODEWITHSUNDEEP
visual-studio-2010msbuild
Harold Bamford
Harold Bamford

Reputation: 1639

For VS2010 (C++) what causes the long delay between clicking on "Build" and when the build actually starts?

I have a simple one-project solution in C++. From the IDE I click on Build Solution and it takes 40 seconds before anything happens. Then 17 seconds to actually do the compiling and linking. If I click Build Solution again, there is another 40 second delay. devenv.exe is busy doing something as it is using 13% of my total CPU during this time.

If I call msbuild directly, it starts immediately. And it doesn't recompile unless it is truly out of date. So it doesn't seem to be a problem with msbuild at all.

I have Googled and chased down lots of articles, but most of them talk about why msbuild is slow or failing, not why the IDE is slow to call msbuild. I've even got an external tool setup using msbuild and it starts immediately. BTW, that tool is based on this:

http://www.hanselman.com/blog/HackParallelMSBuildsFromWithinTheVisualStudioIDE.aspx

I have checked for missing files using the devenv.exe.config change and I do get items like:

devenv.exe Information: 0 :     
Project 'C:\Users\...\XFPMon\XFPMon.vcxproj' not up to date because 2 build outputs were missing.   
devenv.exe Information: 0 :     
up to date is missing: 'C:\WINDOWS\TEMP\AEXAM\AEX7C29.TMP'  
devenv.exe Information: 0 :     
up to date is missing: 'C:\WINDOWS\TEMP\AEXAM\AEX7C28.TMP'

The change to devenv.exe.config was to insert these:

<system.diagnostics>
    <switches>
        <add name="CPS" value="4" />
    </switches>
</system.diagnostics>

and then use DbgView to trace the output during the build. I cannot imagine why devenv.exe would think that TEMP files would be saved between builds.

I have even deleted the Debug and Release directories and compiled from scratch. Still the 40 second delay.

If I do a Rebuild Solution, another 40 second delay.

But if I do a Clean Solution, it runs instantly!

Does anybody have a clue as to what is causing the delay?

Thanks!

EDIT: Further information. I have 8 cores, 12 GB RAM, and a 256 GB SSD, so this little machine has the raw horsepower.

When devenv.exe is in the 40 second delay period, it is drawing a total of 13% of the CPU. When the compilation starts, it drops to less than 1%. The memory usage changes very little. It starts at 458.2MB, rises to 459.9MB during the 40 second delay, and then jumps to 463.1MB immediately after the compilation (if any) finishes.

Upvotes: 2

Views: 812

Answers (1)

Harold Bamford
Harold Bamford

Reputation: 1639

Well, I found the problem. An Addin was taking exponential time to process the .rc and .rc2 files. The Addin was put in many months ago and did not start showing this problem until the size of .rc file grew enough to cause the (poorly-designed) regex to run very slowly.

Worse, I wrote the Addin! And have been using it on several machines for about a year with no problems. Previous versions of the Addin were written in C++ using PCRE regular expressions and never had a problem (even after 5 years of use). But this was a rewrite using C# and .NET Regex, which apparently behaves differently.

I fixed the problem by rewriting the code to avoid the need for some of the backtracking. Simple enough to do, but irritating that it was necessary for C# Regex.

The key to discovering the problem was to start devenv.exe with the /resetaddin option. With this, a build starts immediately. Then it was just a matter of figuring out which addin. I just hadn't done this as I hadn't changed addins for months.

This problem showed up when the .rc file was as small as 12K. I have tested the new version on a 262K .rc file and it runs in 123 ms.

Sigh.

Upvotes: 2

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