Tuesday, August 12, 2008

Slow in Visual Studio debugging

My visual studio has working pretty hard lately. It take minutes to start debug or even compile. I search through the net and found some methods in which would improve the performance of the Visual Studio debuggin performance.

The symbol information for diasymreader.dll tells the debugger that it's symbols are on \\cpvsbuild\....\diasymreader.pdb. When you debug a process which has diasymreader loaded, the debugger will try and get the symbols for you.

Unfortunately, this is not at all what you want. There are two work around:
1) Edit your lmhosts file and edit it so that cpvsbuild has an address of ''. Using a hex editor, open diasymreader.dll and find \\cpvsbuild and change it to some local non-existent path of the same length (i.e. replace '\\c' with 'c:\')

2) Verify that you are not suffering from an issue I call "Dueling Assembly References". I describe how to both detect and fix this condition in this blog post. If you are ever doing a build and see the compilation appear to pause in the "Validating Web Site" phase of compilation (meaning no output occurs in the output window for more than a few seconds), then it is likely that you are running into this problem. Use the techniques outlined in this blog post to fix it.

3) Keep the number of files in your /app_code directory small. If you end up having a lot of class files within this directory, I'd recommend you instead add a separate class library project to your VS solution and move these classes within that instead since class library projects compile faster than compiling classes in the /app_code directory. This isn't usually an issue if you just have a small number of files in /app_code, but if you have lots of directories or dozens of files you will be able to get speed improvements by moving these files into a separate class library project and then reference that project from your web-site instead. One other thing to be aware of is that whenever you switch from source to design-view within the VS HTML designer, the designer causes the /app_code directory to be compiled before the designer surface loads. The reason for this is so that you can host controls defined within /app_code in the designer. If you don't have an /app_code directory, or only have a few files defined within it, the page designer will be able to load much quicker (since it doesn't need to perform a big compilation first).

3) Enable the on-demand compilation option for your web-site projects. To enable this, right-click on your web-site project and pull up the project properties page. Click the "Build" tab on the left to pull up its build settings. Within the "Build" tab settings page change the F5 Start Action from "Build Web Site" to either the "Build Page" or "No Build" option. Then make sure to uncheck the "Build Web site as part of solution" checkbox:

3) If you have a very large project, or are working on an application with many other developers, you might want to consider splitting it up into multiple "sub-web" projects. I wouldn't necessarily recommend this for performance reasons (unless you have thousands and thousands of pages it probably doesn't make a huge difference), but it can sometimes make it easier to help manage a large project. Please read this past blog-post of mine on creating sub-web projects to learn how to use this.

4) Consider adding a VS 2005 Web Deployment project to your solution for deep verification. I mentioned above that one downside of using the VS 2005 Web Application Project option was that it only compiled the code-behind source code of your pages, and didn't do a deeper verification of the actual .aspx markup (so it will miss cases where you have a mis-typed tag in your .aspx markup). This provides the same level of verification support that VS 2003 provided (so you aren't loosing anything from that), but not as deep as the Web Site Project option. One way you can still get this level of verification with VS 2005 Web Application Projects is to optionally add a VS 2005 Web Deployment Project into your solution (web deployment projects work with both web-site and web-application solutions). You can configure this to run only when building "release" or "staging" builds of your solution (to avoid taking a build hit at development time), and use it to provide a deep verification of both your content and source code prior to shipping your app.

5) Watch out for Virus Checkers, Spy-Bots, and Search/Indexing Tools

VS hits the file-system a lot, and obviously needs to reparse any file within a project that has changed the next time it compiles. One issue I've seen reported several times are cases where virus scanners, spy-bot detecters, and/or desktop search indexing tools end up monitoring a directory containing a project a little too closely, and continually change the timestamps of these files (they don't alter the contents of the file - but they do change a last touched timestamp that VS also uses). This then causes a pattern of: you make a change, rebuild, and then in the background the virus/search tool goes in and re-searches/re-checks the file and marks it as altered - which then causes VS to have to re-build it again. Check for this if you are seeing build performance issues, and consider disabling the directories you are working on from being scanned by other programs. I've also seen reports of certain Spybot utilities causing extreme slowness with VS debugging - so you might want to verify that you aren't having issues with those either.

6) Turn off AutoToolboxPopulate in the Windows Forms Designer Options

There is an option in VS 2005 that will cause VS to automatically populate the toolbox with any controls you compile as part of your solution. This is a useful feature when developing controls since it updates them when you build, but I've seen a few reports from people who find that it can cause VS to end up taking a long time (almost like a hang) in some circumstances. Note that this applies both to Windows Forms and Web Projects. To disable this option, select the Tools->Options menu item, and then unselect the Windows Forms Designer/General/AutoToolboxPopulate checkbox option (for a thread on this see: http://forums.asp.net/1108115/ShowPost.aspx).

7) Examine which 3rd party packages are running in Visual Studio

There are a lot of great 3rd party VS packages that you can plug into Visual Studio. These deliver big productivity wins, and offer tons of features. Occasionally I've seen issues where performance or stability is being affected by them though. This is often true in cases where an older version (or beta) of one of these packages is being used (always keep an eye out for when a manufacturer updates them with bug-fixes). If you are seeing issues with performance or stability, you might want to look at trying a VS configuration where you uninstall any additional packages to see if this makes a difference. If so, you can work with the 3rd party manufacturer to identify the issue.

8) Download and install the latest patch for your Visual Studio at MSDN.

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