ThreadPool.UnsafeQueueUserWorkItem Method

Definition

Namespace:

System.Threading

Assembly:

System.Threading.ThreadPool.dll

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

Queues the specified work item object to the thread pool.

public:
 static bool UnsafeQueueUserWorkItem(System::Threading::IThreadPoolWorkItem ^ callBack, bool preferLocal);

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

static member UnsafeQueueUserWorkItem : System.Threading.IThreadPoolWorkItem * bool -> bool

Public Shared Function UnsafeQueueUserWorkItem (callBack As IThreadPoolWorkItem, preferLocal As Boolean) As Boolean

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

Boolean

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

Exceptions

ArgumentNullException

callback is null.

ArgumentOutOfRangeException

The work item is a Task.

OutOfMemoryException

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.

UnsafeQueueUserWorkItem(WaitCallback, Object)

Source:

ThreadPoolWorkQueue.cs

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

public:
 static bool UnsafeQueueUserWorkItem(System::Threading::WaitCallback ^ callBack, System::Object ^ state);

public static bool UnsafeQueueUserWorkItem (System.Threading.WaitCallback callBack, object? state);

static member UnsafeQueueUserWorkItem : System.Threading.WaitCallback * obj -> bool

Public Shared Function UnsafeQueueUserWorkItem (callBack As WaitCallback, state As Object) As Boolean

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

Boolean

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

Exceptions

SecurityException

The caller does not have the required permission.

ApplicationException

An out-of-memory condition was encountered.

OutOfMemoryException

The work item could not be queued.

ArgumentNullException

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

• The Managed Thread Pool

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

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.

public:
generic <typename TState>
 static bool UnsafeQueueUserWorkItem(Action<TState> ^ callBack, TState state, bool preferLocal);

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

static member UnsafeQueueUserWorkItem : Action<'State> * 'State * bool -> bool

Public Shared Function UnsafeQueueUserWorkItem(Of TState) (callBack As Action(Of TState), state As TState, preferLocal As Boolean) As Boolean

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

Boolean

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

Exceptions

ArgumentNullException

callback is null.

NotSupportedException

The work item could not be queued.