Congrats to Chris Keyser and all the authors/contributors for shipping the updated Version 2 of the SharePoint Developers Guidance.. must have free resource if you are doing development with SharePoint.

Guidance for building collaborative applications that extend your LOB systems

The guidance provides value for experienced developers just starting in SharePoint development as well as experienced SharePoint developers looking to expand their skills.

If you are new to SharePoint development, the first step is to study the Training Management application, which is based on Windows SharePoint Services. The documentation and the application can help developers understand the fundamentals of SharePoint development, and compliments other training resources and publications.

For those that already are experienced in developing SharePoint applications, or who have gone through the Training Management application, the Partner Portal application and SharePoint Guidance library demonstrate these advanced areas. You can explore the guidance and Partner Portal reference implementation based upon your areas of interest. The general guidance refers into areas of the reference implementation that illustrate the covered concepts.

This guide enhances product documentation by applying the information to a realistic business situation illustrated in the reference implementations. In many cases, the guidance refers to the product documentation. You can use the guidance to gain initial understanding. You can then use the product documentation for deeper understanding.

Quick Links:

http://www.microsoft.com/spg
http://www.codeplex.com/spg
Download here

What’s included:

Component	Description
SharePoint Guidance Library	A set of reusable components that helps developers manage configuration, build repositories for SharePoint lists, log traces and events, and use service location.
Guide	The documentation includes a variety of topics, such as how to use design and application patterns, how to integrate LOB systems with SharePoint applications, building scalable applications, upgrading SharePoint applications, and using SharePoint capabilities to create, and deploy content. It also includes the design decisions made for the Partner Portal and Training Management applications and explanations of their implementations.
Contoso Partner Portal Reference Implementation	This SharePoint application shows how Contoso created an extranet where it can interact with its partners. Among the items demonstrated are techniques for building manageable and scalable enterprise applications, and how to incorporate publishing and page composition features, flexible navigation, collaboration sites, and LOB integration. It includes more advanced techniques than the Training Management reference implementation and requires Microsoft Office SharePoint Server 2007 with Service Pack 1 or Service Pack 2.
Contoso Training Management Reference Implementation	This SharePoint application illustrates how the Contoso Human Resources department manages its training course offerings. It shows how to solve many basic SharePoint challenges that you might encounter when you develop your own applications. Windows SharePoint Services 3.0 is required.

Channel 9 videos

· Setting up the Contoso RI

· Walkthrough of the Contoso Reference Implementation

· How to use the configuration component?

· How to use the logging components?

· How to use the SharePoint Service Locator?

Authors and Contributors

The Developing SharePoint Applications guidance was produced by the following individuals:

• Larry Brader, Francis Cheung, RoAnn Corbisier, Nelly Delgado, Chris Keyser, Erwin van der Valk, Blaine Wastell, Hanz Zhang (Microsoft Corporation)
• Charles Cho, Mike Chorey (Avanade)
• Kishore Kadiveti, Allvin Muthunayagam, VenkataAppaji Sirangi (Tata Consultancy Services)
• Colin Campbell, Roberta Leibovitz (Modeled Computation LLC)
• Robert L. Bogue (Thor Projects LLC)
• Todd Baginski (Advaiya, Inc)
• Andrew Connell (Critical Path Training)
• John Daniels (Analysts International)
• Tina Burden, Sharon Smith (TinaTech Inc)
• Veronica Ruiz (CXR Design)
• Richard Burte (ChannelCatalyst.com, Inc.)

Many thanks to the following advisors who provided invaluable assistance:

• Microsoft Contributors and Reviewers: Mike Ammerlaan, Paul Andrew, Luca Bandinelli, Eric Charran, Todd Haugen, Rob Howard, Roger Lamb, Steve Peschka, Jim Sturms, Simon Skaria, Aaron Weiker, Mike Wise
• External Contributors and Reviewers: Reza Alirezaei, Darrin Bishop, Jackson Chackungal, Spencer Harbar, Faraz Khan, Matthew McDermott, Maurice Prather, Eric Shupps, Ethan Wilansky, Andrew Woodward

Find up-to-date guidance about how to write Microsoft Office SharePoint Server 2007 applications and customizations that perform well, avoid common pitfalls, and best use the features of the SharePoint object model.

http://msdn.microsoft.com/en-us/office/dd638301.aspx

Today the Microsoft SharePoint Product Team announced the SPDisposeCheck utility here and also at Paul Andrew’s blog here. You can download the free SPDisposeCheck utility in the MSDN Code Gallery http://code.msdn.microsoft.com/SPDisposeCheck .

The SPDisposeCheck utility will assist you dig through your custom SharePoint MSIL assemblies (DLL’s and EXE’s) looking for areas in your code that may require “closer examination” and might lead to Dispose() related memory leaks.  It’s important to note that this tool is not a replacement for developers to learn and understand the ins and outs of the SharePoint Dispose() guidance and how it is implemented in their custom code.  A manual code review is still required to cast out ‘false positives’ that the tool may produce in the output report.  During internal field tests we received feedback that the tool can help identify areas in the code that may have been overlooked even by the most experienced SharePoint developers. As a final step in development we encourage you to frequently review your ULS logs for Dispose() related leaks that have occurred while the code is executing.  Note SharePoint’s instrumentation writes to the ULS logs when it finds SPSite and SPWeb objects that were not disposed as expected.

The original MSDN article Best Practices: Using Disposable Windows SharePoint Services Objects was updated 1/30/09 and the Dispose() guidance is in sync with the content on this blog and the SPDisposeCheck tool.  If you have not done so in a while check out my original blog post “SharePoint 2007 and WSS 3.0 Dispose Patterns by Example” which has several updated Dispose() guidance and edge cases including RootWeb and ParentWeb changes.  You can find all the source code examples on this blog in the Visual Studio 2008 solution SPDisposeExamples packaged with the SPDisposeCheck utility installer.

Understanding the latest Dispose() guidance from Microsoft, scanning with SPDisposeCheck frequently throughout the Software Development Life Cycle (SDLC), and examining the SharePoint ULS logs for evidence of Dispose() related leaks during runtime can help you reduce the probability of unnecessary memory pressure resulting in poor performing SharePoint applications.

The following edge case applies to MOSS 2007 (and not WSS 3.0).  When using the following pattern the property Microsoft.Office.Server.UserProfiles.PersonalSite requires a Dispose() call before leaving scope if you use the property in your code.  Below is an example of a common usage of PersonalSite property.

void PersonalSiteLeak()
{
    // open a site collection
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        UserProfileManager profileManager = new UserProfileManager(ServerContext.GetContext(siteCollection));
        UserProfile profile = profileManager.GetUserProfile("domain\\username");
        SPSite personalSite = profile.PersonalSite;    // will leak
    }
}

void PersonalSiteNoLeak()
{
    // open a site collection
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        UserProfileManager profileManager = new UserProfileManager(ServerContext.GetContext(siteCollection));
        UserProfile profile = profileManager.GetUserProfile("domain\\username");
        using (SPSite personalSite = profile.PersonalSite)
        {
            // ...
        }
    }
}

From a web context performance perspective it is more efficient to get your UserProfile object in the following example:

UserProfile myProfile = ProfileLoader.GetProfileLoader().GetUserProfile();
using (SPSite personalSite = myProfile.PersonalSite)
{
     // ...
}

Note the use of ProfileLoader to get the shared UserProfile instance for my own profile.  There is no need to open a fresh SPSite in the case where you’re browsing a page.  Additionally, if your web part is designed to be placed on a My Site, there is even a shared PersonalSite instance that will be disposed for you and does not require you to call Dispose() with this technique:

IPersonalPage currentMySitePage = this.Page as IPersonalPage;
if (currentMySitePage != null && !currentMySitePage.IsProfileError)
{
     SPSite personalSite = currentMySitePage.PersonalSite; // will not leak
     // ...
}

Thanks to Microsoft’s Anant Dimiri and Bryant Fong for their contributions!

Paul Andrew just announced on the Microsoft SharePoint Team Blog that a new Community Technology Preview (CTP) version of the Visual Studio extensions for SharePoint 1.3 (VSeWSS 1.3) is now publically available on Microsoft Connect site.

New Features in VSeWSS 1.3

• The extensions now install on x64 bit OS. Visual Studio 2008 and SharePoint must be already installed.
• Command Line Build option for TFS and MSBuild integration
• Separate WSP Package and Retract commands. You can now build the WSP without deploying it
• SPSolGen to Support Exporting from Content Management Publishing Sites
• New Item Template for RootFiles Deployment
• Automatically Remove conflicting existing features on development SharePoint server
• WSP View New Feature Dialog Improvements: scope, receiver checkbox, element checkbox
• WSP View can now be used to merge features and it blocks site features being merged into web features
• Allow adding separate binary files such as Workflow assemblies
• Some refactoring allowing for Web Part renaming and removing lines from feature.xml Item Removed
• Allow selection of GAC or BIN deployment for Web Part Project not including CAS generation
• Increase visibility of hidden features that VSeWSS creates
• Add fast update deploy for DLL only or file only changes to solutions
• Numerous Bug Fixes and improvements to error messages

Paul Andrew (Microsoft SharePoint Product Group) announced the SPDisposeCheck utility at the Tech·Ed EMEA Developers Conference today.  The SPDisposeCheck command line utility will be released soon (North American Winter) and will recursively scan any destination folder that you specify containing custom WSS 3.0 and Microsoft SharePoint Server 2007 .NET assemblies (scanning MSIL and not the source code itself) looking for SharePoint specific Dispose() best practices (or lack thereof) as listed in the guidance on MSDN Best Practices: Using Disposable Windows SharePoint Services Objects , Best Practices: Common Coding Issues When Using the SharePoint Object Model , and my blog SharePoint 2007 and WSS 3.0 Dispose Patterns by Example .  SPDisposeCheck utility is intended to help quickly scan through a large amount of custom SharePoint code in order to direct an experienced SharePoint developer to areas of concern with regards to proper usage of Dispose().

Additional SPDisposeCheck information:

• For developer workstations, not to be run on production
• Built on FX Cop technology the tool opens assemblies and validates them against the Microsoft published guidance (however, not compatible with FX Cop)
• Output will contain warnings messages for Dispose() method
• May include “false positives” so expert analysis is required
• Contact Microsoft support if you need assistance now

Special thanks to Microsoft’s Sean Thompson (Microsoft PFE), Scott Harris, Paul Andrew, and Stefan Goßner.  In addition, I’d like to thank the folks in the field including the MOSS MVP’s and Microsoft Services and Support (MCS/Premier/PFE/CSS) for their feedback and testing.

Last Updated: January 30, 2009

[New] – The original MSDN article Best Practices: Using Disposable Windows SharePoint Services Objects was updated 1/30/2009 and the Dispose() guidance is now in sync with the content on this blog and the new SPDisposeCheck automated Dispose() code review tool.

Overview

Windows SharePoint Services (WSS 3.0) and Microsoft Office SharePoint Server (MOSS 2007) have some gotchas with serious implications that every SharePoint application developer needs to be intimately familiar with before deploying into production MOSS 2007 farms.  In particular, Microsoft.SharePoint.SPSite , Microsoft.SharePoint.SPWeb , and the often overlooked (MOSS 2007) Microsoft.SharePoint.Publishing objects need to be carefully examined and disposed of properly in order to avoid potential memory leaks. My original objective with this blog post was to consolidate several different reliable sources compiled by Microsoft's top Subject Matter Experts (SME’s) into a Uber-Dispose quick reference which could be used to increase developer awareness of the current Microsoft Guidance.  I’ve been working closely with the SharePoint Product Group as well as the top Microsoft Support and Services SME’s to help carve out the information you see here.  I plan to keep this blog post updated with the latest official guidance from Microsoft and while there are more verbose resources available elsewhere the primary objective is to provide lots of samples in a quick reference format.  Pre-requisites: The intended audience for this guidance is a seasoned .NET developer who currently is or will be developing custom SharePoint solutions with Visual Studio 2005/2008.

Quick Reference - SharePoint Example Dispose() Patterns

• WSS 3.0
  • Microsoft.SharePoint.SPList.BreakRoleInheritance() method [Updated]
  • Microsoft.SharePoint.SPSite new() operator
  • Microsoft.SharePoint.SPSite.OpenWeb() method
  • Microsoft.SharePoint.SPSite.AllWebs[] indexer
  • Microsoft.SharePoint.SPSite.RootWeb, LockIssue, Owner, and SecondaryContact properties [Updated]
  • Microsoft.SharePoint.SPSite.AllWebs.Add() method
  • Microsoft.SharePoint.SPWeb.GetLimitedWebPartManager() method
  • Microsoft.SharePoint.SPWeb.ParentWeb property [Updated]
  • Microsoft.SharePoint.SPWeb.Webs property
  • Microsoft.SharePoint.SPWeb.Webs.Add() method [Updated]
  • Microsoft.SharePoint.SPWebCollection.Add() method [Updated]
  • Microsoft.SharePoint.WebControls.SPControl GetContextSite() and GetContextWeb() methods
  • Microsoft.SharePoint.SPContext Current.Site / SPContext.Site and SPContext.Current.Web / SPContext.Web properties
  • Microsoft.SharePoint.Administration.SPSiteCollection[] indexer
  • Microsoft.SharePoint.Administration.Add() method
• MOSS 2007
  • Microsoft.SharePoint.Publishing.GetPublishingWebs() method
  • Microsoft.SharePoint.Publishing.PublishingWebCollection.Add() method
  • Microsoft.SharePoint.Publishing.PublishingWeb.GetVariation() method [Updated]
  • Microsoft.Office.Server.UserProfiles.PersonalSite property [Updated]
• Obsolete
  • Microsoft.SharePoint.Portal.SiteData.Area.Web property [Updated]

Why Dispose?

SPSite and SPWeb classes both implement the IDisposable interface.  Microsoft .NET requires objects that implement the IDisposable interface to properly cleanup the unmanaged resources by explicitly calling the Dispose() method when you are finished using them.  Internally, SPSite and SPWeb both hold references to an "internal class Microsoft.SharePoint.Library.SPRequest" which holds on to unmanaged COM resources.  The consequence of not explicitly disposing unmanaged resources in a timely fashion can lead to not having enough memory for further allocations and quickly consumes memory. Under the hood, when reviewing dump files we see the that the managed objects used by SPSite and SPWeb are relatively small and it's the unmanaged resources that are most concerning and account for approximately 1MB to 2MB for each object instance!  Omitting to explicitly call Dispose() means the .NET (non-deterministic) garbage collector gets out of sync with the finalizer and the unmanaged memory does not get reclaimed in a timely manner possibly blocking future memory allocations. For further reading I recommend reviewing Stefan Goßner's blog Dealing with Memory Pressure problems in MOSS/WSS .

The unmanaged memory leaks can grow very quickly especially when traversing through frequently called areas like site navigation code and item event receivers.  The lack of proper Dispose() hygiene can increase your risk of frequent IIS Application Domain recycles (see Steve Sheppard's blog Overlapped Recycling And SharePoint: Why SharePoint Requires It), Out Of Memory (OOM) exceptions, high memory consumption, and poor performing SharePoint production environments.

To Dispose or not Dispose?! That is the question...

To make matters more confusing for SharePoint developers there are times when SPSite and SPWeb objects should not be disposed and are cleaned up by SharePoint and ASP.NET after page processing is completed.  In addition, there are cases when developers indirectly call a property on a object that creates and holds an internal reference to a SPSite or SPWeb object (for example SPSite.ParentWeb property).  Understanding the origin and the scope the object was created is paramount when determining whether or not to explicitly call dispose.

Dispose Patterns

When writing customized SharePoint code you need to be aware of the scope and context of each SPSite, SPWeb objects lifetime.  When objects are created and destroyed in the same method or iteration scope (foreach or do/while loop) they are the easiest to clean handle.  Things become more complex to review when developers create objects in one method and dispose in another.  Areas to be aware of are assigning objects to class variables or static/global variables which may hold on to the object reference across method calls.  The content in this blog post is a combination of Product Group Guidance along with any edge cases that have been discovered in the field through support incidents.

Try / finally using() Dispose()

Make certain that the objects listed here which need to be properly Disposed by your application code is wrapped within a using(), try/finally, or try/catch/finally block.  Failure to do so can lead to unexpected memory leaks as there is no other way to guarantee that your Dispose will be reached in the event of an exception.  See my updated guidance here.

Troubleshooting Dispose Related Leaks

Recently the SPDisposeCheck utility was announced by Paul Andrew from the Microsoft SharePoint Product Group which was published 1/29/09 here.  This command line utility will help scan your custom MOSS and WSS 3.0 .NET assemblies (MSIL not your original source code) automatically scanning for the guidance listed on this blog post.  SPDisposeCheck will produce a summary report calling your attention to areas in your code you that you need to closely examine for possible Dispose() related leaks.  After you have completed your initial scan with SPDisposeCheck you should examine the SharePoint ULS logs to help further verify that no Dispose() edge cases will be introduced into your shared development, test, and production environments.  Stefan Goßner (Microsoft Support Escalation Engineer) has created guidance on using the ULS logs to Troubleshooting SPSite/SPWeb leaks in WSS v3 and MOSS 2007 .  See also Stefan’s Disposing SPWeb and SPSite objects for additional info.  For advanced troubleshooting you can ($) contact Microsoft Support or if you have a Premier Contract you can engage Microsoft Premier Support’s Developer Advisory Services (DAS) or Premier Field Engineering (PFE) resources for advanced troubleshooting, debugging, and proactive advisory services including custom code reviews.

SharePoint Memory Internals

400 Level – (Optional read) It’s very important for the developer of the application code to understand when is the optimal time for code optimization and performance reasons to hold on to and release the proper SharePoint objects in a timely fashion.  As SharePoint Application developers you should be familiar with the public SPSite and SPWeb objects but internally to get their work done the real managed object that holds onto the unmanaged heap is SPRequestInternalClass which is internal to a wrapper class SPRequest.

Internally we use a RCW (runtime callable wrapper) which is essentially a finalizable object (there are subtle differences but they don’t really come into play here).    If that object is no longer rooted, the finalizer (teardown of the RCW) will release the native memory.   However, like normal finalizers the RCW teardown is performed by a single finalizer thread which generally can’t keep up with cleaning these objects if they’re being leaked many times per second.

Not releasing the SharePoint objects in a timely fashion can lead to poor memory hygiene including excessive fragmentation, pinning, and OOM exceptions building very quickly.  Problematic code which fails to properly dispose objects in a timely fashion becomes exacerbated especially in x32bit environments with a large number of sites.  We encourage all Enterprise SharePoint farms to use x64bit versions of the OS and MOSS to take advantage of the additional addressable memory.

Note resources other than just memory are effected by not properly disposing your object in a timely fashion.  For example, SQL Server establishes a 1:1 connection with each SPRequest object and it lives up to the release of the internal SPRequest object (which is used by your SPSite and SPWeb object).

Microsoft.SharePoint.SPList

• [Updated] - SPList.BreakRoleInheritance() method no longer requires list.ParentWeb.Dispose() to be executed after calling BreakRoleInheritance() due to the updated ParentWeb guidance (see ParentWeb) later in this blog post.

Microsoft.SharePoint.SPSite

• [Updated] - RootWeb property no longer requires Dispose() to be called on itself as previously indicated in the Whitepaper Best Practices: Using Disposable Windows SharePoint Services Objects .  See my blog post here for more detail.  In addition, properties LockIssue, Owner, and SecondaryContact internally used the RootWeb property.  Based on the updated Microsoft guidance for RootWeb there is no longer a requirement to explicitly Dispose on any of these properties.  Note that the owning SPSite object must be properly Disposed (or not Disposed in the case of SPContext) as described by the rules listed elsewhere in this blog.
  
  
• new SPSite() operator - Instantiating SPSite objects with the new operator needs to be disposed.

Note: With C# you can automatically have the Dispose() called for you when the object leaves the scope by wrapping the code with the using() { } statement.

void CreatingSPSiteLeak()
{
    SPSite siteCollection = new SPSite("http://moss");
    // siteCollection leaked
}

void CreatingSPSiteExplicitDisposeNoLeak()
{
    SPSite siteCollection = null;
    try
    {
        siteCollection = new SPSite("http://moss");
    }
    finally
    {
        if (siteCollection != null)
            siteCollection.Dispose();
    }
}

CreatingSPSiteWithAutomaticDisposeNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
    } // SPSite object siteCollection.Dispose() automatically called
}

• OpenWeb() returns a SPWeb object which needs to be disposed.

Avoid the following pattern which collapses SPSite and SPWeb calls.  The example returns the SPWeb site object wrapped by a using statement which gets disposed but there is no way to dispose the underlying SPSite object.

void OpenWebLeak()
{
    using (SPWeb web = new SPSite(SPContext.Current.Web.Url).OpenWeb())
    {
        // SPSite leaked !
    } // SPWeb object web.Dispose() automatically called
}

void OpenWebNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
        } // SPWeb object web.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called
}

• AllWebs[] Indexer returns SPWeb object that needs to be disposed to avoid aggregation of memory which can lead to memory pressure when running on a site collection with large number of sub sites.

void AllWebsForEachLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb outerWeb = siteCollection.OpenWeb())
        {
            foreach (SPWeb innerWeb in siteCollection.AllWebs)
            {
                // explicit dispose here to avoid OOM's with large # of webs
            }
        } // SPWeb object outerWeb.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

void AllWebsForEachNoLeakOrMemoryOOM()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb outerWeb = siteCollection.OpenWeb())
        {
            foreach (SPWeb innerWeb in siteCollection.AllWebs)
            {
                try
                {
                    // ...
                }
                finally
                {
                    if(innerWeb != null)
                        innerWeb.Dispose();
                }
            }
        } // SPWeb object outerWeb.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

void AllWebsIndexerLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        SPWeb web = siteCollection.AllWebs[0];
        // SPWeb web leaked
    }  // SPSite object siteCollection.Dispose() automatically called 
}

void AllWebsIndexerNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.AllWebs[0])
        {
        } // SPWeb object web.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

• AllWebs.Add() returns a instance of SPWeb object which needs to be disposed.

void AllWebsAddLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        SPWeb web = siteCollection.AllWebs.Add("site-relative URL");
        // SPWeb web Leaked
    }  // SPSite object siteCollection.Dispose() automatically called 
}

void AllWebsAddNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.AllWebs.Add("site-relative URL"))
        {
        } // SPWeb object web.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

Microsoft.SharePoint.SPWeb

• [Updated] – ParentWeb property no longer requires Dispose() as previously indicated in the Whitepaper Best Practices: Using Disposable Windows SharePoint Services Objects .  Note that the owning SPSite object must be properly Disposed (or not Disposed in the case of SPContext) as described by the rules listed elsewhere in this blog.
  
  
• GetLimitedWebPartManager() method returns a SPWeb object which needs to be disposed. 

void SPLimitedWebPartManagerLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            SPFile page = web.GetFile("Source_Folder_Name/Source_Page");
            SPLimitedWebPartManager webPartManager = page.GetLimitedWebPartManager(PersonalizationScope.Shared);
            // SPWeb object webPartManager.Web leaked
        } // SPWeb object web.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

void SPLimitedWebPartManagerNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            SPFile page = web.GetFile("Source_Folder_Name/Source_Page");
            using (SPLimitedWebPartManager webPartManager = page.GetLimitedWebPartManager(PersonalizationScope.Shared))
            {
                try
                {
                    // ...
                }
                finally
                {
                    webPartManager.Web.Dispose();
                }
            }
        } // SPWeb object web.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}
 

• SPWeb.Webs property returns SPWebCollection object that needs to be disposed.

void WebsLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb outerWeb = siteCollection.OpenWeb())
        {
            foreach (SPWeb innerWeb in outerWeb.Webs)
            {
                // SPWeb innerWeb leak
            }
        } // SPWeb object outerWeb.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

void WebsNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb outerWeb = siteCollection.OpenWeb())
        {
            foreach (SPWeb innerWeb in outerWeb.Webs)
            {
                try //should be 1st statement after foreach
                {
                    // ...
                }
                finally
                {
                    if(innerWeb != null)
                        innerWeb.Dispose();
                }
            }
        } // SPWeb object outerWeb.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

• [Updated] – SPWeb.Webs.Add() method returns a SPWeb object that needs to be disposed.

void WebsAddLeak(string strWebUrl)
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            SPWeb addedWeb = web.Webs.Add(strWebUrl);   // will leak

        } // SPWeb object web.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called
}

void WebsAddNoLeak(string strWebUrl)
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            using (SPWeb addedWeb = web.Webs.Add(strWebUrl))
            {
                //..
            }

        } // SPWeb object web.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called
}

Microsoft.SharePoint.SPWebCollection

• [Updated] – SPWebCollection.Add() method returns a SPWeb object that needs to be disposed.

void SPWebCollectionAddLeak(string strWebUrl)
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb outerWeb = siteCollection.OpenWeb())
        {
            SPWebCollection webCollection = siteCollection.AllWebs; // no AllWebs leak just getting reference
            SPWeb innerWeb = webCollection.Add(strWebUrl);  // must dispose of innerWeb
            // innerWeb Leak
        } // SPWeb object outerWeb.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

void SPWebCollectionAddNoLeak(string strWebUrl)
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb outerWeb = siteCollection.OpenWeb())
        {
            SPWebCollection webCollection = siteCollection.AllWebs; // no AllWebs leak just getting reference
            using (SPWeb innerWeb = webCollection.Add(strWebUrl))
            {
                //...
            }
        } // SPWeb object outerWeb.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

Microsoft.SharePoint.WebControls.SPControl

• GetContextSite(Context) and GetContextWeb(Context) methods return SPSite and SPWeb objects respectively that DO NOT need a call to Dispose() and will be cleaned up automatically by SharePoint.

void SPControlBADPractice()
{
    SPSite siteCollection = SPControl.GetContextSite(Context);
    siteCollection.Dispose();   // DO NOT DO THIS
    SPWeb web = SPControl.GetContextWeb(Context);
    web.Dispose();  // DO NOT DO THIS
}

void SPControlBestPractice()
{
    SPSite siteCollection = SPControl.GetContextSite(Context);
    SPWeb web = SPControl.GetContextWeb(Context);
    // Do NOT call Dispose()
}

Microsoft.SharePoint.SPContext

• SPContext.Current.Site & SPContext.Site as well as SPContext.Current.Web & SPContext.Web properties return SPSite and SPWeb objects respectively that DO NOT need a call to Dispose() and will be disposed automatically by SharePoint.

void SPContextBADPractice()
{
    SPSite siteCollection = SPContext.Current.Site;
    siteCollection.Dispose(); // DO NOT DO THIS
    SPWeb web = SPContext.Current.Web;
    web.Dispose(); // DO NOT DO THIS
}

void SPContextBestPractice()
{
    SPSite siteCollection = SPContext.Current.Site;
    SPWeb web = SPContext.Current.Web;
    // Do NOT call Dispose()
}

Microsoft.SharePoint.Publishing

• GetPublishingWebs() method returns a PublishingWebCollection that you are required to call Close() on each of the returned PublishingWeb objects inside the loop.  Note that when you are only calling GetPublishingWeb(SPWeb) method (not the collection) you should not call Close().

void PublishingWebCollectionLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            // passing in web you own, no dispose needed on outerPubWeb
            PublishingWeb outerPubWeb = PublishingWeb.GetPublishingWeb(web);

            PublishingWebCollection pubWebCollection = outerPubWeb.GetPublishingWebs();
            foreach (PublishingWeb innerPubWeb in pubWebCollection)
            {
                // innerPubWeb leak
            }
            // PublishingWeb will leak for each innerPubWeb referenced
        } // SPWeb object web.Dispose() automatically called
    } // SPSite object siteCollection.Dispose() automatically called
}

void PublishingWebCollectionNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            // passing in web you own, no dispose needed on outerPubWeb
            PublishingWeb outerPubWeb = PublishingWeb.GetPublishingWeb(web);
            PublishingWebCollection pubWebCollection = outerPubWeb.GetPublishingWebs();
            foreach (PublishingWeb innerPubWeb in pubWebCollection)
            {
                try
                {
                    // ...
                }
                finally
                {
                    if(innerPubWeb != null)
                        innerPubWeb.Close();
                }
            }
            // outerPubWeb.Close(); not needed and if called will log warning in ULS log
        }  // SPWeb object web.Dispose() automatically called
    } // SPSite object siteCollection.Dispose() automatically called
}

void GetPublishingWebNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            // passing in web you own, no dispose needed on singlePubWeb
            PublishingWeb singlePubWeb = PublishingWeb.GetPublishingWeb(web);
        } // SPWeb object web.Dispose() automatically called
    } // SPSite object siteCollection.Dispose() automatically called
}

• [Updated] PublishingWeb.GetVariation() method returns a PublishingWeb object which which needs to be explicitly closed.

void GetVariationLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            PublishingWeb publishingWeb = PublishingWeb.GetPublishingWeb(web);  // Passing in web so no Close() needed
            VariationLabel variationLabel = Variations.Current.UserAccessibleLabels[0];
            PublishingWeb variationPublishingWeb = publishingWeb.GetVariation(variationLabel);  // must be Closed()
            // ...
        } // SPWeb object web.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

void GetVariationNoLeak()
{
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        using (SPWeb web = siteCollection.OpenWeb())
        {
            PublishingWeb variationPublishingWeb = null;
            try
            {
                PublishingWeb publishingWeb = PublishingWeb.GetPublishingWeb(web);  // Passing in web so no Close() needed
                VariationLabel variationLabel = Variations.Current.UserAccessibleLabels[0];
                variationPublishingWeb = publishingWeb.GetVariation(variationLabel);  // must be Closed()
                // ...
            }
            finally
            {
                if(variationPublishingWeb != null)
                    variationPublishingWeb.Close();
            }
        } // SPWeb object outerWeb.Dispose() automatically called
    }  // SPSite object siteCollection.Dispose() automatically called 
}

• PublishingWebCollection.Add() method requires you to call Close() on the returned PublishingWeb object.  For a code sample refer to the MOSS SDK GetPublishingWebs() sample.

Microsoft.Office.Server.UserProfiles

UserProfiles.PersonalSite requires a Dispose() call before leaving scope if you use the property in your code.  For addition code optimization information please see my blog post here.

void PersonalSiteLeak()
{
    // open a site collection
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        UserProfileManager profileManager = new UserProfileManager(ServerContext.GetContext(siteCollection));
        UserProfile profile = profileManager.GetUserProfile("domain\\username");
        SPSite personalSite = profile.PersonalSite;    // will leak
    }
}

void PersonalSiteNoLeak()
{
    // open a site collection
    using (SPSite siteCollection = new SPSite("http://moss"))
    {
        UserProfileManager profileManager = new UserProfileManager(ServerContext.GetContext(siteCollection));
        UserProfile profile = profileManager.GetUserProfile("domain\\username");
        using (SPSite personalSite = profile.PersonalSite)
        {
            // ...
        }
    }
}

Microsoft.SharePoint.Administration

• SPSiteCollection[] indexer returns a SPSite object which needs to be disposed.

void SPSiteCollectionIndexerLeak()
{
    using (SPSite siteCollectionOuter = new SPSite("http://moss"))
    {
        SPWebApplication webApp = siteCollectionOuter.WebApplication;
        SPSiteCollection siteCollections = webApp.Sites;

        SPSite siteCollectionInner = siteCollections[0];
        // SPSite siteCollectionInner leak 
    } // SPSite object siteCollectionOuter.Dispose() automatically called
}

void SPSiteCollectionIndexerNoLeak()
{
    using (SPSite siteCollectionOuter = new SPSite("http://moss"))
    {
        SPSite siteCollectionInner = null;
        try
        {
            SPWebApplication webApp = siteCollectionOuter.WebApplication;
            SPSiteCollection siteCollections = webApp.Sites;

            siteCollectionInner = siteCollections[0];
        }
        finally
        {
            if (siteCollectionInner != null)
                siteCollectionInner.Dispose();
        }
    } // SPSite object siteCollectionOuter.Dispose() automatically called
}

void SPSiteCollectionForEachLeak()
{
    using (SPSite siteCollectionOuter = new SPSite("http://moss"))
    {
        SPWebApplication webApp = siteCollectionOuter.WebApplication;
        SPSiteCollection siteCollections = webApp.Sites;

        foreach (SPSite siteCollectionInner in siteCollections)
        {
            // SPSite siteCollectionInner leak
        }
    } // SPSite object siteCollectionOuter.Dispose() automatically called
}

void SPSiteCollectionForEachNoLeak()
{
    using (SPSite siteCollectionOuter = new SPSite("http://moss"))
    {
        SPWebApplication webApp = siteCollectionOuter.WebApplication;
        SPSiteCollection siteCollections = webApp.Sites;

        foreach (SPSite siteCollectionInner in siteCollections)
        {
            try
            {
                // ...
            }
            finally
            {
                if(siteCollectionInner != null)
                    siteCollectionInner.Dispose();
            }
        }
    } // SPSite object siteCollectionOuter.Dispose() automatically called
}

• Add() returns a SPSite object which needs to be disposed.

void SPSiteCollectionAddLeak()
{
    SPWebApplication webApp = new SPSite("http://moss").WebApplication;
    SPSiteCollection siteCollections = webApp.Sites;
    SPSite siteCollection = siteCollections.Add("sites/myNewSiteCollection", "DOMAIN\\User", "roger.lamb@litwareinc.com");
    // SPSite siteCollection leak
}

void SPSiteCollectionAddNoLeak()
{
    SPWebApplication webApp = new SPSite("http://moss").WebApplication;
    SPSiteCollection siteCollections = webApp.Sites;
    using (SPSite siteCollection = siteCollections.Add("sites/myNewSiteCollection", "DOMAIN\\User", "roger.lamb@litwareinc.com"))
    {
    } // SPSite object siteCollection.Dispose() automatically called
}

Microsoft.SharePoint.Portal.SiteData.Area (Obsolete)

• [Updated] - Area.Web property creates a SPWeb object that needs to be Disposed().  Although the Area class is obsolete in MOSS 2007 it is still of concern when migrating legacy code.

public void AreaWebLeak()
{
    // AreaManager and Area are obsolete in MOSS but this should still be noted
    Area area = AreaManager.GetArea(PortalContext.Current, new Guid("{GUID}"));
    SPWeb areaWeb = area.Web;   // this SPWeb object must be disposed
    string str = areaWeb.Title;
    // SPWeb areaWeb leak
}

public void AreaWebNoLeak()
{
    // AreaManager and Area are obsolete in MOSS but this should still be noted
    Area area = AreaManager.GetArea(PortalContext.Current, new Guid("{GUID}"));
    using (SPWeb areaWeb = area.Web)
    {
        string str = areaWeb.Title;
    }
}

Cross Method Dispose Patterns

• The following example demonstrates the common practice of holding onto the SPSite and SPWeb objects across methods in a class.  There are times where this design pattern is required however make sure you don't overlook the appropriate time to call dispose when you are finished with the cross method calls.  Below is an example of this pattern and shows and example of a leak of both SPSite and SPWeb when the class is torn down.

public class CrossMethodLeak
{
    private SPSite _siteCollection = null;
    private SPWeb _web = null;

    public void MethodA()
    {
        _siteCollection = new SPSite("http://moss");
        _web = _siteCollection.OpenWeb();
    }

    public void MethodB()
    {
        if (_web != null)
        {
            string title = _web.Title;
        }
    }

    public void MethodC()
    {
        if (_web != null)
        {
            string name = _web.Name;
        }
    }
}

Summary

If you have extended MOSS 2007 or WSS 3.0 with custom code you should digest this post carefully to avoid expensive consequences commonly found in production environments.  For a more verbose explanation of many of the topics covered in this blog post I suggest you read Scott Harris's MSDN White Papers Best Practices: Using Disposable Windows SharePoint Services Objects and Best Practices: Common Coding Issues When Using the SharePoint Object Model .

Special thanks to my Microsoft colleagues Scott Harris, Stefan Goßner, Steve Sheppard, Sean Thompson, Lisa Guthrie, Cliff Green, and Rick Caudle for reviewing and helping contribute to this blog post.