Parallel.For<TLocal> Method (Int32, Int32, Func<TLocal>, Func<Int32, ParallelLoopState, TLocal, TLocal>, Action<TLocal>)
Executes a for loop with thread-local data in which iterations may run in parallel, and the state of the loop can be monitored and manipulated.
Assembly: mscorlib (in mscorlib.dll)
public static ParallelLoopResult For<TLocal>( int fromInclusive, int toExclusive, Func<TLocal> localInit, Func<int, ParallelLoopState, TLocal, TLocal> body, Action<TLocal> localFinally )
Type Parameters
- TLocal
The type of the thread-local data.
Parameters
- fromInclusive
- Type: System.Int32
The start index, inclusive.
- toExclusive
- Type: System.Int32
The end index, exclusive.
- localInit
- Type: System.Func<TLocal>
The function delegate that returns the initial state of the local data for each thread.
- body
- Type: System.Func<Int32, ParallelLoopState, TLocal, TLocal>
The delegate that is invoked once per iteration.
- localFinally
- Type: System.Action<TLocal>
The delegate that performs a final action on the local state of each thread.
Return Value
Type: System.Threading.Tasks.ParallelLoopResultA ParallelLoopResult structure that contains information on what portion of the loop completed.
| Exception | Condition |
|---|---|
| ArgumentNullException |
The exception that is thrown when the body argument is null. -or- The exception that is thrown when the localInit or localFinally argument is null. -or- The exception that is thrown when the localFinally argument is null. |
| AggregateException |
The exception that contains all the individual exceptions thrown on all threads. |
The body delegate is invoked once for each value in the iteration range: [fromInclusive, toExclusive). It is provided with the following parameters: the iteration count (an Int32), a ParallelLoopState instance that may be used to break out of the loop prematurely, and some local state that may be shared amongst iterations that execute on the same thread.
The localInit delegate is invoked once for each thread that participates in the loop's execution and returns the initial local state for each of those threads. These initial states are passed to the first body invocations on each thread. Then, every subsequent body invocation returns a possibly modified state value that is passed to the next body invocation. Finally, the last body invocation on each thread returns a state value that is passed to the localFinally delegate. The localFinally delegate is invoked once per thread to perform a final action on each thread's local state. This delegate might be invoked concurrently on multiple threads; therefore, you must synchronize access to any shared variables.
If fromInclusive is greater than or equal to toExclusive, then the method returns immediately without performing any iterations.
For an example that uses this method, see How to: Write a Parallel.For Loop That Has Thread-Local Variables.
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.
