ThreadLocal<T> 类

  • 参考

定义

命名空间:
System.Threading
程序集:
System.Threading.dll
程序集:
mscorlib.dll
程序集:
netstandard.dll

提供数据的线程本地存储。

generic <typename T>
public ref class ThreadLocal : IDisposable
public class ThreadLocal<T> : IDisposable
type ThreadLocal<'T> = class
    interface IDisposable
Public Class ThreadLocal(Of T)
Implements IDisposable

类型参数

T

指定按线程存储的数据类型。

继承
Object
ThreadLocal<T>
实现
IDisposable

示例

下面的示例演示如何使用 ThreadLocal<T>：

using System;
using System.Threading;
using System.Threading.Tasks;

class ThreadLocalDemo
{
    
        // Demonstrates:
        //      ThreadLocal(T) constructor
        //      ThreadLocal(T).Value
        //      One usage of ThreadLocal(T)
        static void Main()
        {
            // Thread-Local variable that yields a name for a thread
            ThreadLocal<string> ThreadName = new ThreadLocal<string>(() =>
            {
                return "Thread" + Thread.CurrentThread.ManagedThreadId;
            });

            // Action that prints out ThreadName for the current thread
            Action action = () =>
            {
                // If ThreadName.IsValueCreated is true, it means that we are not the
                // first action to run on this thread.
                bool repeat = ThreadName.IsValueCreated;

                Console.WriteLine("ThreadName = {0} {1}", ThreadName.Value, repeat ? "(repeat)" : "");
            };

            // Launch eight of them.  On 4 cores or less, you should see some repeat ThreadNames
            Parallel.Invoke(action, action, action, action, action, action, action, action);

            // Dispose when you are done
            ThreadName.Dispose();
        }
}
// This multithreading example can produce different outputs for each 'action' invocation and will vary with each run.
// Therefore, the example output will resemble but may not exactly match the following output (from a 4 core processor):
// ThreadName = Thread5 
// ThreadName = Thread6 
// ThreadName = Thread4 
// ThreadName = Thread6 (repeat)
// ThreadName = Thread1 
// ThreadName = Thread4 (repeat)
// ThreadName = Thread7 
// ThreadName = Thread5 (repeat)

Imports System.Threading
Imports System.Threading.Tasks

Module ThreadLocalDemo

    ' Demonstrates:
    ' ThreadLocal(T) constructor
    ' ThreadLocal(T).Value
    ' One usage of ThreadLocal(T)
    Sub Main()
        ' Thread-Local variable that yields a name for a thread
        Dim ThreadName As New ThreadLocal(Of String)(
            Function()
                Return "Thread" & Thread.CurrentThread.ManagedThreadId
            End Function)

        ' Action that prints out ThreadName for the current thread
        Dim action As Action =
            Sub()
                ' If ThreadName.IsValueCreated is true, it means that we are not the
                ' first action to run on this thread.
                Dim repeat As Boolean = ThreadName.IsValueCreated

                Console.WriteLine("ThreadName = {0} {1}", ThreadName.Value, If(repeat, "(repeat)", ""))
            End Sub

        ' Launch eight of them. On 4 cores or less, you should see some repeat ThreadNames
        Parallel.Invoke(action, action, action, action, action, action, action, action)

        ' Dispose when you are done
        ThreadName.Dispose()
    End Sub
End Module
' This multithreading example can produce different outputs for each 'action' invocation and will vary with each run.
' Therefore, the example output will resemble but may not exactly match the following output (from a 4 core processor):
' ThreadName = Thread5 
' ThreadName = Thread6 
' ThreadName = Thread4 
' ThreadName = Thread6 (repeat)
' ThreadName = Thread1 
' ThreadName = Thread4 (repeat)
' ThreadName = Thread7 
' ThreadName = Thread5 (repeat)

构造函数

ThreadLocal<T>()

初始化 ThreadLocal<T> 实例。
ThreadLocal<T>(Boolean)

初始化 ThreadLocal<T> 实例并指定是否可从任意线程访问所有值。
ThreadLocal<T>(Func<T>)

使用指定的 valueFactory 函数初始化 ThreadLocal<T> 实例。
ThreadLocal<T>(Func<T>, Boolean)

使用指定的 valueFactory 函数和指示是否可从任意线程访问所有值的标志初始化 ThreadLocal<T> 实例。

属性

IsValueCreated

获取是否在当前线程上初始化 Value。
Value

获取或设置当前线程的此实例的值。
Values

获取一个列表，其中包含所有已访问此实例的线程存储的值。

方法

Dispose()

释放 ThreadLocal<T> 类的当前实例所使用的所有资源。
Dispose(Boolean)

释放该 ThreadLocal<T> 实例使用的资源。
Equals(Object)

确定指定对象是否等于当前对象。

(继承自 Object)
Finalize()

释放该 ThreadLocal<T> 实例使用的资源。
GetHashCode()

作为默认哈希函数。

(继承自 Object)
GetType()

获取当前实例的 Type。

(继承自 Object)
MemberwiseClone()

创建当前 Object 的浅表副本。

(继承自 Object)
ToString()

创建并返回当前线程的此实例的字符串表示形式。

适用于

线程安全性

除此外 Dispose()，所有公共成员和受保护成员 ThreadLocal<T> 都是线程安全的，并且可以从多个线程并发使用。 为 Value 属性 IsValueCreated 返回的值特定于访问属性的线程。

另请参阅