ThreadPool.UnsafeQueueUserWorkItem Method

Definition

Overloads

UnsafeQueueUserWorkItem(IThreadPoolWorkItem, Boolean)

Queues the specified work item object to the thread pool.

UnsafeQueueUserWorkItem(WaitCallback, Object)

Queues the specified delegate to the thread pool, but does not propagate the calling stack to the worker thread.

UnsafeQueueUserWorkItem<TState>(Action<TState>, TState, Boolean)

Queues a method specified by an Action<T> delegate for execution, and specifies an object containing data to be used by the method. The method executes when a thread pool thread becomes available.

UnsafeQueueUserWorkItem(IThreadPoolWorkItem, Boolean)

Source:
ThreadPoolWorkQueue.cs
Source:
ThreadPoolWorkQueue.cs
Source:
ThreadPoolWorkQueue.cs

Queues the specified work item object to the thread pool.

C#
public static bool UnsafeQueueUserWorkItem(System.Threading.IThreadPoolWorkItem callBack, bool preferLocal);

Parameters

callBack
IThreadPoolWorkItem

The work item to invoke when a thread in the thread pool picks up the work item.

preferLocal
Boolean

true to prefer queueing the work item in a queue close to the current thread; false to prefer queueing the work item to the thread pool's shared queue.

Returns

true if the method succeeds; OutOfMemoryException is thrown if the work item could not be queued.

Exceptions

callback is null.

The work item is a Task.

The work item could not be queued.

Remarks

The thread pool will invoke the work item's Execute() method. It is the responsibility of that work item to propagate ExecutionContext if it's needed; the thread pool will not do so.

Applies to

.NET 9 and other versions
Product Versions
.NET Core 3.0, Core 3.1, 5, 6, 7, 8, 9

UnsafeQueueUserWorkItem(WaitCallback, Object)

Source:
ThreadPoolWorkQueue.cs
Source:
ThreadPoolWorkQueue.cs
Source:
ThreadPoolWorkQueue.cs

Queues the specified delegate to the thread pool, but does not propagate the calling stack to the worker thread.

C#
public static bool UnsafeQueueUserWorkItem(System.Threading.WaitCallback callBack, object? state);
C#
public static bool UnsafeQueueUserWorkItem(System.Threading.WaitCallback callBack, object state);
C#
[System.Security.SecurityCritical]
public static bool UnsafeQueueUserWorkItem(System.Threading.WaitCallback callBack, object state);

Parameters

callBack
WaitCallback

A WaitCallback that represents the delegate to invoke when a thread in the thread pool picks up the work item.

state
Object

The object that is passed to the delegate when serviced from the thread pool.

Returns

true if the method succeeds; OutOfMemoryException is thrown if the work item could not be queued.

Attributes

Exceptions

The caller does not have the required permission.

An out-of-memory condition was encountered.

The work item could not be queued.

callBack is null.

Remarks

Unlike the QueueUserWorkItem method, UnsafeQueueUserWorkItem does not propagate the calling stack to the worker thread. This allows code to lose the calling stack and thereby to elevate its security privileges.

Caution

Using UnsafeQueueUserWorkItem could inadvertently open up a security hole. Code access security bases its permission checks on the permissions of all the callers on the stack. When work is queued on a thread pool thread using UnsafeQueueUserWorkItem, the stack of the thread pool thread will not have the context of the actual callers. Malicious code might be able exploit this to avoid permission checks.

See also

Applies to

.NET 9 and other versions
Product Versions
.NET Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 2.0, 2.1

UnsafeQueueUserWorkItem<TState>(Action<TState>, TState, Boolean)

Source:
ThreadPoolWorkQueue.cs
Source:
ThreadPoolWorkQueue.cs
Source:
ThreadPoolWorkQueue.cs

Queues a method specified by an Action<T> delegate for execution, and specifies an object containing data to be used by the method. The method executes when a thread pool thread becomes available.

C#
public static bool UnsafeQueueUserWorkItem<TState>(Action<TState> callBack, TState state, bool preferLocal);

Type Parameters

TState

The type of elements of state.

Parameters

callBack
Action<TState>

A delegate representing the method to execute.

state
TState

An object containing data to be used by the method.

preferLocal
Boolean

true to prefer queueing the work item in a queue close to the current thread; false to prefer queueing the work item to the thread pool's shared queue.

Returns

true if the method is successfully queued; NotSupportedException is thrown if the work item could not be queued.

Exceptions

callback is null.

The work item could not be queued.

Applies to

.NET 9 and other versions
Product Versions
.NET Core 3.0, Core 3.1, 5, 6, 7, 8, 9