Article
11/18/2011

ThreadStaticAttribute Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Indicates that the value of a static field is unique for each thread.

Inheritance Hierarchy

System.Object
System.Attribute
System.ThreadStaticAttribute

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
<AttributeUsageAttribute(AttributeTargets.Field, Inherited := False)> _
<ComVisibleAttribute(True)> _
Public Class ThreadStaticAttribute _
    Inherits Attribute

[AttributeUsageAttribute(AttributeTargets.Field, Inherited = false)]
[ComVisibleAttribute(true)]
public class ThreadStaticAttribute : Attribute

The ThreadStaticAttribute type exposes the following members.

Constructors

	Name	Description
	ThreadStaticAttribute	Initializes a new instance of the ThreadStaticAttribute class.

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Methods

	Name	Description
	Equals	Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Returns the hash code for this instance. (Inherited from Attribute.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	Match	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

A static field (Shared in Visual Basic) marked with ThreadStaticAttribute is not shared between threads. Each executing thread has a separate instance of the field, and independently sets and gets values for that field. If the field is accessed on a different thread, it will contain a different value.

Note:
Do not specify initial values for fields marked with ThreadStaticAttribute, because such initialization occurs only once, when the class constructor executes, and therefore affects only one thread. If you do not specify an initial value, you can rely on the field being initialized to its default value if it is a value type, or to nulla null reference (Nothing in Visual Basic) (Nothing in Visual Basic) if it is a reference type.

Do not specify initial values for fields marked with ThreadStaticAttribute, because such initialization occurs only once, when the class constructor executes, and therefore affects only one thread. If you do not specify an initial value, you can rely on the field being initialized to its default value if it is a value type, or to nulla null reference (Nothing in Visual Basic) (Nothing in Visual Basic) if it is a reference type.

Use this attribute as it is, and do not derive from it. The following is an example of ThreadStaticAttribute syntax:

[ThreadStatic]
static int value;

<ThreadStatic> _
Shared value As Integer

Platform Notes

Silverlight for Windows Phone

ThreadStaticAttribute is not supported in Silverlight for Windows Phone.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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