SPDisposeCheck - This should be in EVERY SharePoint developer's toolbox

Today Microsoft released a tool on MSDN Code Gallery called SPDisposeCheck. It will look at your code in a SharePoint to make sure you are properly disposing objects to ensure you aren't consuming more memory than you need to be. This tool is incredibly helpful as this one one issue that many customers run into unknowingly. IMHO, all your projects should be run though SPDisposeCheck before deployment.

Microsoft is also updating the dispose best practices article in the SDK that will walk you through how to use this tool as well as updated info along disposing of SharePoint objects.

Run, don't walk, and download this tool today!

» MSDN Code Gallery: SharePoint Dispose Checker

Technorati Tags: sharepoint,spdisposecheck,dispose,wss,moss,best practice

posted on Thursday, January 29, 2009 1:40 PM

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# re: SPDisposeCheck - This should be in EVERY SharePoint developer's toolbox 1/30/2009 8:21 AM Kristian Kjær

A little warning (beware that the observations below are from a pre-release version of the tool):

Don’t use the tool without proper considerations. Especially you should notice:
1. If the tool says you have 0 (zero) errors (memory leaks) you should NOT be happy. The tool tells you for example to dispose uses of the RootWeb property. This is not always right. You should NOT dispose SPContext.Current.Site.RootWeb. If you do this and SPContext.Current.Site.RootWeb == SPContext.Current.Web you get an exception.
2. It does NOT find all memory leaks. In fact it only finds the most obvious leaks. Consider the following pattern (and yes, it is not good code, but I have seen it A LOT in various "live" systems):

public List<SPListItem> GetItems(SPQuery query) {
using (SPSite site = new SPSite(“http://localhost”) {
using (SPWeb web = site.RootWeb) {
var items = web.Lists[“MyList”].GetItems(query);
return items.Cast<SPListItem>().ToList();
}
}
}

public string DoSomething(SPQuery query) {
var sb = new StringBuilder();
var items = GetItems(query);
foreach(var item in items) {
sb.AppendLine(item[“Title”]);
}
return sb.ToString();
}

In this case you have a memory leak and the tool won’t find it. For those who don’t see where the leak is, it arises when the method, DoSomething, uses the SPListItem. Internally MOSS will recreate the owner SPWeb object, but won’t dispose it. The user has to do this (or better, write better code!) by calling item.ParentList.ParentWeb.Dispose()!!

# re: SPDisposeCheck - This should be in EVERY SharePoint developer's toolbox 1/30/2009 5:59 PM AC [MVP MOSS]

Kristan-
First, you should test against the live tool as #1 was fixed in the released version. As for #2, read the article I linked to... it provides guidance around this. It was never meant to find ALL leaks and cases of dispose... just as the article says.

# re: SPDisposeCheck - This should be in EVERY SharePoint developer's toolbox 1/31/2009 1:15 AM Michhes

Heads up, the dispose best practices article is now live.

Also worth noting Roger Lamb's dedicated blog post on this subject has been at the forefront of this topic for a long time now, communicating the latest revisions prior to their incorporation into the guidance.

http://blogs.msdn.com/rogerla/archive/2008/02/12/sharepoint-2007-and-wss-3-0-dispose-patterns-by-example.aspx

# re: SPDisposeCheck - This should be in EVERY SharePoint developer's toolbox 1/31/2009 8:32 AM AC [MVP MOSS]

Michhes-
Agreed... hence why it's linked on the SPDisposeCheck download page. I suspect you haven't looked at the new download page or the new release before commenting.

# re: SPDisposeCheck - This should be in EVERY SharePoint developer's toolbox 2/2/2009 5:38 PM Matt

Definitely cool stuff! I've added an AfterBuild target to my projects so that I can get this to run each time I build, without having to mess with the command line, a la:

<Target Name="AfterBuild">
<Exec Command='"C:\Program Files\Microsoft\SharePoint Dispose Check\SPDisposeCheck.exe" "$(TargetPath)"' />
</Target>

Thanks for sharing the links.

# re: SPDisposeCheck - This should be in EVERY SharePoint developer's toolbox 9/10/2010 1:38 AM Eric Fang

Many thanks, Paul!

I didn't realize that under certain cases "MOSS will recreate the owner SPWeb object".

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