SharePoint underground (Unmanaged Code and SharePoint Internals)

Unmanaged code and SharePoint Internals
Karla Ponce
Neudesic

Who is Karla Ponce?
Microsoft MVP
More than 10 years of experience
Active speaker
I’m not any of that…
Twitter - @SPKarlaPonce
Blog – http://SharePointWithAttitudecom

Unmanaged code vs. Managed code
Why should I care?
SharePoint object model Overview
SharePoint Internals: SPRequest
Common Issues
Best Practices
Owssvr.dll
Agenda

Tambien se habla español.

SharePoint uses unmanaged code to perform the majority of the work. The managed part of it is much smaller than the unmanaged part.
Premise

Unmanaged code vs Managed code

Managed Code:
It compiles to Intermediate Language (IL).
It runs and is managed by the CLR.
The runtime provides services such as security, memory management, threading, etc.
Unmanaged Code:
It compiles directly to machine code.
It does not run and is not managed by the CLR.
It doesn't get the services of the runtime.
Unmanaged code vs Managed code

For an understanding of how things work:
OM is a wrapper of the unmanaged code.
The managed part is small; the unmanaged part of is much larger.
Understanding will help us to:
Troubleshoot issues, fix bugs and do performance tuning.
Write scalable, quality and solid code.
Avoid memory issues and poor performance.
Why should I care?

SharePoint Dlls

Site Architecture and Object Model

SharePoint Internals

Potentially excessive number of SPRequest objects (9) currently unreleased on thread 6. Ensure that this object or its parent (such as an SPWeb or SPSite) is being properly disposed. This object is holding on to a separate native heap.
Common Issues

An SPRequest object was reclaimed by the garbage collector instead of being explicitly freed. To avoid wasting system resources, dispose of this object or its parent (such as an SPSite or SPWeb) as soon as you are done using it. Allocation Id: {6E0B2F08-BEE0-43D4-BEDA-FDA2A43F40D8} To determine where this object was allocated, create a registry key at HKEY_LOCAL_MACHINESOFTWAREMicrosoftShared ToolsWeb Server ExtensionsHeapSettings. Then create a new DWORD named SPRequestStackTrace with the value 1 under this key.
Common Issues

Disposing objects
Using objects efficiently
Performance concerns – Memory allocation
Write scalable code
Unmanaged Code: Best Practices

Caching Objects that contain an embedded reference to SPWeb or SPSite objects.
SPWeb and SPSite contain reference to unmanaged code (not thread safety) and should not be cached.
Using objects efficiently

Bad Coding Practice:
Caching objects and Thread Safety

Applying a lock:

Good code practice:

Always ensure to correctly dispose all SPWeb and SPSite. Dispose all objects implementing the IDisposable interface .
Object disposal: Dispose method; using clause; try, catch, and finally blocks.
SPDisposeCheck, free tool that inspects your assemblies for coding practices that cause memory leaks because of improper handling and disposal of SharePoint objects.
Disposing SharePoint Objects

Bad coding practice

Good coding practice

Using(SPSite mySite = new SPSite(“http://moss”)
{
SPWeb web1= mySite.OpenWeb();
SPWeb web2= mySite.RootWeb();
SPWeb web3 = SPContext.Current.Site.OpenWeb();
}

Performance concerns – Memory allocation
How many SPRequest objects are open in parallel?
Do SPRequest objects still exist at the end of the thread that created it?

SharePoint 2010 Developer Dashboard

The principal DLL of the unmanaged code is owssvr.dll
OWSSVR.DLL is an ISAPI extension registered in IIS and its methods can be called directly via an HTTP request to /_vti_bin/owssvr.dll.
Returning all data for a SharePoint list, including its XSD:http://WebApp/[site]/_vti_bin/owssvr.dll?Cmd=Display&List={ListGuid}&Query=*&XMLDATA=TRUE
Owssvr.dll

SharePoint executes all the read/write operations to the DB through unmanaged code.
SPWeb and SPSite contain a reference to the unmanaged code.
Unmanaged objects are created in form of a SPRequest.
Because SPRequest does not run under the .NET Runtime, we have to dispose those objects to avoid memory issues.
Summary

Object Model:
http://msdn.microsoft.com/en-us/library/ms430674(v=office.12).aspx
Best Practices: Disposing SharePoint Objects
http://msdn.microsoft.com/en-us/library/aa973248.aspx
URL Protocol:
http://msdn.microsoft.com/en-us/library/ms478653.aspx
SharePoint Dispose Checker Tool
http://code.msdn.microsoft.com/SPDisposeCheck
Resources

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SharePoint underground (Unmanaged Code and SharePoint Internals)

by Karla Ponce

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