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ParallelForEach<T> Class

Enumerates the elements of a collection and executes an embedded statement for each element of the collection in parallel.

System.Object
  System.Activities.Activity
    System.Activities.NativeActivity
      System.Activities.Statements.ParallelForEach<T>

Namespace:  System.Activities.Statements
Assembly:  System.Activities (in System.Activities.dll)

[ContentPropertyAttribute("Body")]
public sealed class ParallelForEach<T> : NativeActivity

Type Parameters

T

The type of the values provided in the Values collection.

The ParallelForEach<T> type exposes the following members.

  NameDescription
Public methodParallelForEach<T>Creates a new instance of the ParallelForEach<T> class.
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  NameDescription
Public propertyBodyThe ActivityAction that is executed once for every value contained in the Values collection.
Protected propertyCacheIdGets the identifier of the cache that is unique within the scope of the workflow definition. (Inherited from Activity.)
Protected propertyCanInduceIdleGets or sets a value that indicates whether the activity can cause the workflow to become idle. (Inherited from NativeActivity.)
Public propertyCompletionConditionEvaluated after each iteration completes.
Protected propertyConstraintsGets a collection of Constraint activities that can be configured to provide validation for the Activity. (Inherited from Activity.)
Public propertyDisplayNameGets or sets an optional friendly name that is used for debugging, validation, exception handling, and tracking. (Inherited from Activity.)
Public propertyIdGets an identifier that is unique in the scope of the workflow definition. (Inherited from Activity.)
Protected propertyImplementationThe execution logic of the activity. (Inherited from NativeActivity.)
Public propertyValuesThe collection of values used as parameters for each iteration of the activity contained in the Body.
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  NameDescription
Protected methodAbortWhen implemented in a derived class, takes actions in response to the activity being aborted. (Inherited from NativeActivity.)
Protected methodCacheMetadata(ActivityMetadata)Not implemented. Use the CacheMetadata(NativeActivityMetadata) method instead. (Inherited from NativeActivity.)
Protected methodCacheMetadata(NativeActivityMetadata)Creates and validates a description of the activity’s arguments, variables, child activities, and activity delegates. (Inherited from NativeActivity.)
Protected methodCancelWhen implemented in a derived class, runs logic to cause graceful early completion of the activity. (Inherited from NativeActivity.)
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodExecuteWhen implemented in a derived class, runs the activity’s execution logic. (Inherited from NativeActivity.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodShouldSerializeDisplayNameIndicates whether the DisplayName property should be serialized. (Inherited from Activity.)
Public methodToStringReturns a String that contains the Id and DisplayName of the Activity. (Inherited from Activity.)
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The embedded statements are scheduled together and run asynchronously, but unless the scheduled activites themselves are asynchronous (such as messaging activities, InvokeMethod, or activities that derive from AsyncCodeActivity), they do not run on separate threads, so each successive activity will only execute when the previously scheduled activity completes or goes idle. If none of the child activities of this activity are asynchronous or go idle, this activity execute in the same way that a ForEach<T> activity does.

The following code sample demonstrates creating a ParallelForEach<T> activity. This example is from the Corporate Purchase Process sample.


// invite all vendors and wait for their proposals
new ParallelForEach<Vendor>
{
    DisplayName = "Get vendor proposals",
    Values = new InArgument<IEnumerable<Vendor>>(ctx =>this.Rfp.Get(ctx).InvitedVendors),
    Body = new ActivityAction<Vendor>()
    {                                    
        Argument = iterationVariableVendor,
        Handler = new Sequence
        {
            Variables = { tmpValue },
            Activities =
            {
                // waits for a vendor proposal (creates a bookmark for a vendor)
                new WaitForVendorProposal 
                { 
                    VendorId = new LambdaValue<int>(ctx =>iterationVariableVendor.Get(ctx).Id) ,
                    Result = new OutArgument<double>(tmpValue)
                },

                // after the vendor proposal is received, it is registered in the Request for Proposals
                new InvokeMethod
                {
                    TargetObject = new InArgument<RequestForProposal>(ctx =>this.Rfp.Get(ctx)),
                    MethodName = "RegisterProposal",
                    Parameters = 
                    {
                        new InArgument<Vendor>(iterationVariableVendor),
                        new InArgument<double>(tmpValue)
                    }
                },
            }
        }                        
    }
},


.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.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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