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Thread.FreeNamedDataSlot Method (String)


Eliminates the association between a name and a slot, for all threads in the process. For better performance, use fields that are marked with the ThreadStaticAttribute attribute instead.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, SharedState = true, 
	ExternalThreading = true)]
public static void FreeNamedDataSlot(
	string name


Type: System.String

The name of the data slot to be freed.


The .NET Framework provides two mechanisms for using thread local storage (TLS): thread-relative static fields (that is, fields that are marked with the ThreadStaticAttribute attribute) and data slots. Thread-relative static fields provide much better performance than data slots, and enable compile-time type checking. For more information about using TLS, see Thread Local Storage: Thread-Relative Static Fields and Data Slots.

After any thread calls FreeNamedDataSlot, any other thread that calls GetNamedDataSlot with the same name will allocate a new slot associated with the name. Subsequent calls to GetNamedDataSlot by any thread will return the new slot. However, any thread that still has a System.LocalDataStoreSlot returned by an earlier call to GetNamedDataSlot can continue to use the old slot.

A slot that has been associated with a name is released only when every LocalDataStoreSlot that was obtained prior to the call to FreeNamedDataSlot has been released and garbage-collected.

Threads use a local store memory mechanism to store thread-specific data. The common language runtime allocates a multi-slot data store array to each process when it is created. The thread can allocate a data slot in the data store, store and retrieve a data value in the slot, and free the slot for reuse after the thread expires. Data slots are unique per thread. No other thread (not even a child thread) can get that data.

This section contains two code examples. The first example shows how to use a field that is marked with the ThreadStaticAttribute attribute to hold thread-specific information. The second example shows how to use a data slot to do the same thing.

First Example

The following example shows how to use a field that is marked with ThreadStaticAttribute to hold thread-specific information. This technique provides better performance than the technique that is shown in the second example.

using System;
using System.Threading;

class Test
    static void Main()
        for(int i = 0; i < 3; i++)
            Thread newThread = new Thread(ThreadData.ThreadStaticDemo);

class ThreadData
    static int threadSpecificData;

    public static void ThreadStaticDemo()
        // Store the managed thread id for each thread in the static
        // variable.
        threadSpecificData = Thread.CurrentThread.ManagedThreadId;

        // Allow other threads time to execute the same code, to show
        // that the static data is unique to each thread.
        Thread.Sleep( 1000 );

        // Display the static data.
        Console.WriteLine( "Data for managed thread {0}: {1}", 
            Thread.CurrentThread.ManagedThreadId, threadSpecificData );

/* This code example produces output similar to the following:

Data for managed thread 4: 4
Data for managed thread 5: 5
Data for managed thread 3: 3

Second Example

The following example demonstrates how to use a named data slot to store thread-specific information.

using System;
using System.Threading;

class Test
    public static void Main()
        Thread[] newThreads = new Thread[4];
        int i;
        for (i = 0; i < newThreads.Length; i++)
            newThreads[i] =
                new Thread(new ThreadStart(Slot.SlotTest));
        for (i = 0; i < newThreads.Length; i++)
            Console.WriteLine("Thread_{0} finished.",

class Slot
    private static Random randomGenerator = new Random();

    public static void SlotTest()
        // Set random data in each thread's data slot.
        int slotData = randomGenerator.Next(1, 200);
        int threadId = Thread.CurrentThread.ManagedThreadId;


        // Show what was saved in the thread's data slot.
        Console.WriteLine("Data stored in thread_{0}'s data slot: {1,3}",
            threadId, slotData);

        // Allow other threads time to execute SetData to show
        // that a thread's data slot is unique to itself.

        int newSlotData =

        if (newSlotData == slotData)
            Console.WriteLine("Data in thread_{0}'s data slot is still: {1,3}",
                threadId, newSlotData);
            Console.WriteLine("Data in thread_{0}'s data slot changed to: {1,3}",
                threadId, newSlotData);

.NET Framework
Available since 1.1
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