ThreadLocal<T> 類別

  • 參考

定義

命名空間:
System.Threading
組件:
System.Threading.dll
組件:
mscorlib.dll
組件:
netstandard.dll

提供資料的執行緒區域儲存區。

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

類型參數

T

指定每個執行緒儲存的資料型別。

繼承
Object
ThreadLocal<T>
實作
IDisposable

範例

下列範例顯示如何使用 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)

建構函式

ThreadLocal<T>()

初始化 ThreadLocal<T> 執行個體。
ThreadLocal<T>(Boolean)

初始化 ThreadLocal<T> 執行個體，並指定是否可從任何執行緒存取所有值。
ThreadLocal<T>(Func<T>)

使用指定的 valueFactory 函式來初始化 ThreadLocal<T> 的執行個體。
ThreadLocal<T>(Func<T>, Boolean)

使用指定的 valueFactory 函式及指出是否可從任何執行緒存取所有值的旗標，初始化 ThreadLocal<T> 執行個體。

屬性

IsValueCreated

取得值，這個值表示 Value 是否已在目前執行緒中完成初始化。
Value

取得或設定目前執行緒的這個執行個體的值。
Values

取得清單，其中包含所有已存取這個實例的執行緒所儲存的值。

方法

Dispose()

釋放 ThreadLocal<T> 類別目前的執行個體所使用的全部資源。
Dispose(Boolean)

釋放這個 ThreadLocal<T> 執行個體所使用的資源。
Equals(Object)

判斷指定的物件是否等於目前的物件。

(繼承來源 Object)
Finalize()

釋放這個 ThreadLocal<T> 執行個體所使用的資源。
GetHashCode()

做為預設雜湊函式。

(繼承來源 Object)
GetType()

取得目前執行個體的 Type。

(繼承來源 Object)
MemberwiseClone()

建立目前 Object 的淺層複製。

(繼承來源 Object)
ToString()

建立並傳回目前執行緒的這個執行個體的字串表示。

適用於

執行緒安全性

除了 Dispose() 之外，的所有公用和受保護成員 ThreadLocal<T> 都是安全線程，而且可以從多個執行緒同時使用。 針對 和 IsValueCreated 屬性所傳 Value 回的值是存取屬性之執行緒的特定值。

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