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TaskScheduler Class

Represents an object that handles the low-level work of queuing tasks onto threads.


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

[<PermissionSetAttribute(SecurityAction.InheritanceDemand, Unrestricted = true)>]
[<HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true, 
    ExternalThreading = true)>]
type TaskScheduler =  class end

The TaskScheduler type exposes the following members.

Protected methodTaskSchedulerInitializes the TaskScheduler.

Public propertyStatic memberCurrentGets the TaskScheduler associated with the currently executing task.
Public propertyStatic memberDefaultGets the default TaskScheduler instance that is provided by the .NET Framework.
Public propertyIdGets the unique ID for this TaskScheduler.
Public propertyMaximumConcurrencyLevelIndicates the maximum concurrency level this TaskScheduler is able to support.

Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeFrees all resources associated with this scheduler. (Overrides Object.Finalize().)
Public methodStatic memberFromCurrentSynchronizationContextCreates a TaskScheduler associated with the current System.Threading.SynchronizationContext.
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Protected methodGetScheduledTasksFor debugger support only, generates an enumerable of Task instances currently queued to the scheduler waiting to be executed.
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodQueueTaskQueues a Task to the scheduler.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Protected methodTryDequeueAttempts to dequeue a Task that was previously queued to this scheduler.
Protected methodTryExecuteTaskAttempts to execute the provided Task on this scheduler.
Protected methodTryExecuteTaskInlineDetermines whether the provided Task can be executed synchronously in this call, and if it can, executes it.

Public eventStatic memberUnobservedTaskExceptionOccurs when a faulted Task's unobserved exception is about to trigger exception escalation policy, which, by default, would terminate the process.

TaskScheduler acts as the extension point for all pluggable scheduling logic. This includes mechanisms such as how to schedule a task for execution, and how scheduled tasks should be exposed to debuggers.

For more information and code examples, see Task Schedulers.

Several sample task schedulers are available on Code Gallery: Samples for Parallel Programming with the .NET Framework 4.


The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization | ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following example is taken from the Parallel Extensions Samples on the MSDN Code Gallery Web site.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

All members of the abstract TaskScheduler type are thread-safe and may be used from multiple threads concurrently.